## Review of preview

Bắt đầu vào lúc Sunday, 3 April 2011, 09:55 PM Sunday, 3 April 2011, 10:02 PM 7 mins 55 giây 0/462 0 out of a maximum of 10 (0%)
Question 1
Điểm : 0/1

The time for a worker to assemble a component is normally distributed with mean 15 minutes and variance 4. Denote the mean assembly times of 16 day-shift workers and 9 night-shift workers by $$\overline{X}$$ and $$\overline{Y}$$, respectively. Assume that the assembly times of the workers are mutually independent. The distribution of  $$\overline{X}$$- $$\overline{Y}$$ is

Chọn một câu trả lời
 a. normal with mean 15 and variance 5/6. b. normal with mean 0 and standard deviation 5/6. c. standard normal. d. normal with mean 0 and standard deviation 25/72.
Không đúng
Điểm: 0/1.
Question 2
Điểm : 0/1
Find the standard deviation for the given sample data:
2  6  2  2  1  4  4  2  4  2  3  8  4  2  2  7  7  2  3  11
Chọn một câu trả lời
 a. 2.6 b. 2.5 c. 2.7 d. 2.4
Không đúng
Điểm: 0/1.
Question 3
Điểm : 0/1

Survey responses of “ good, better, best”.  which type of data is?

Chọn một câu trả lời
 a. Nomial b. Interval c. Ordinal d. Ratio
Không đúng
Điểm: 0/1.
Question 4
Điểm : 0/1
Find the mean for the binomial distribution which has the stated values of n and p. Round answer to the nearest tenth.

n = 20; p = 3/5
Chọn một câu trả lời
 a. 11.5 b. 12.3 c. 12.0 d. 12.7
Không đúng
Điểm: 0/1.
Question 5
Điểm : 0/1
Assume that X has a normal distribution with the mean is μ = 15.2 and the standard deviation is σ = 0.9. Find the probability that X is greater than 16.1.
Chọn một câu trả lời
 a. 0.1587 b. 0.1550 c. 0.8413 d. 0.1357
Không đúng
Điểm: 0/1.
Question 6
Điểm : 0/1

The manufacturer of a refrigerator system for beer kegs produces refrigerators that are supposed to maintain a true mean temperature, μ, of 45°F, ideal for a certain type of German pilsner. The owner of the brewery does not agree with the refrigerator manufacturer, and claims he can prove that the true mean temperature is incorrect. Assuming that a hypothesis test of the claim has been conducted and that the conclusion is to reject the null hypothesis, state the conclusion in nontechnical terms.

Chọn một câu trả lời
 a. There is not sufficient evidence to support the claim that the mean temperature is different from 45°F b. There is sufficient evidence to support the claim that the mean temperature is equal to 45°F c. There is sufficient evidence to support the claim that the mean temperature is different from 45°F d. There is not sufficient evidence to support the claim that the mean temperature is equal to 45°F
Không đúng
Điểm: 0/1.
Question 7
Điểm : 0/1

It is desired to estimate the average total compensation of CEOs in the Service industry. Data were randomly collected from 18 CEOs and the 97% confidence interval was calculated to be ($2181260,$5836180). Which of the following interpretations is correct?

Chọn một câu trả lời
 a. We are 97% confident that the average total compensation of all CEOs in the Service industry falls in the interval $2181260 to$5836180. b. In the population of Service industry CEOs, 97% of them will have total compensations that fall in the interval $2181260 to$5836180. c. We are 97% confident that the mean of the sampled CEOs falls in the interval $2181260 to$5836180. d. 97% of the sampled total compensation values fell between $2181260 and$5836180.
Không đúng
Điểm: 0/1.
Question 8
Điểm : 0/1

A bag of colored candies contains 20 red, 25 yellow, and 35 orange candies. An experiment consists of randomly choosing one candy from the bag and recording its color. What is the sample space for this experiment?

Chọn một câu trả lời
 a. {80} b. {red, yellow, orange} c. {20, 25, 35} d. {1/4, 5/16, 7/16}
Không đúng
Điểm: 0/1.
Question 9
Điểm : 0/1

The probability is 2% that an electrical connector that is kept dry fails during the warranty period of a portable computer. If the connector is ever wet, the probability of a failure during the warranty period is 10%. If 80% of the connectors are kept dry and 20% are wet, what proportion of connectors fail during the warranty period?

Chọn một câu trả lời
 a. 0.08 b. 0.6 c. 0.036 d. 0.014
Không đúng
Điểm: 0/1.
Question 10
Điểm : 0/1
The amount of pyridoxine (in grams) per multiple vitamin is normally distributed with $$\mu= 110$$ grams and $$\sigma = 25$$ grams. A sample of vitamins is to be selected. What is the probability that the sample mean will be less than 100 grams? Let $$P(Z<-2)=0.023;P(Z<-0.4)=0.421;P(Z<0.07)=0.529;P(Z<0.75)=0.673$$.
Chọn một câu trả lời
 a. 0.023 b. 0.529 c. 0.673 d. 0.421
Không đúng
Điểm: 0/1.
Question 11
Điểm : 0/1
A card game is played in which the player wins if a face card is drawn (king, queen, jack) from a deck of 52 cards. If the player plays 10 times, what is the expected number of wins for the player?
Chọn một câu trả lời
 a. 1.78 b. 0.58 c. 2.31 d. 1.33
Không đúng
Điểm: 0/1.
Question 12
Điểm : 0/1
Researchers are concerned that the weight of the average American school child is increasing implying, among other things, that children’s clothing should be manufactured and marketed in larger sizes. If $$X$$ is the weight of school children sampled in a nationwide study, then $$X$$ is an example of
Chọn một câu trả lời
 a. a discrete random variable. b. a categorical random variable. c. a parameter. d. a continuous random variable.
Không đúng
Điểm: 0/1.
Question 13
Điểm : 0/1
In a recent survey, 80% of the community favored building a police substation in their neighborhood. If 15 citizens are chosen, what is the standard deviation of the number favoring the substation?
Chọn một câu trả lời
 a. 2.40 b. 0.55 c. 0.98 d. 1.55
Không đúng
Điểm: 0/1.
Question 14
Điểm : 0/1

Find the critical value or values of x2 based on the given information.

H1: σ < 0.629

n = 19

α = 0.025

Chọn một câu trả lời
 a. 7.015 b. 8.231 c. 8.907 d. 31.526
Không đúng
Điểm: 0/1.
Question 15
Điểm : 0/1
A company has 2 machines that produce widgets. An older machine produces 23% defective widgets, while the new machine produces only 8% defective widgets. In addition, the new machine produces 3 times as many widgets as the older machine does. What is the probability that a randomly chosen widget produced by the company is defective?
Chọn một câu trả lời
 a. 0.156 b. 0.078 c. 0.310 d. 0.1175
Không đúng
Điểm: 0/1.
Question 16
Điểm : 0/1
Find the origin data from the sterm-and-leaf  plot

Chọn một câu trả lời
 a. b. c. d.
Không đúng
Điểm: 0/1.
Question 17
Điểm : 0/1

The grade point averages for 10 randomly selected students are listed below. Construct a 90% confidence interval for the population standard deviation, $$\sigma.$$ Assume the data are normally distributed.

2.0 3.2 1.8 2.9 0.9 4.0 3.3 2.9 3.6 0.8

Chọn một câu trả lời
 a. (1.10, 2.01) b. (0.81, 1.83) c. (0.32, 0.85) d. (0.53, 1.01)
Không đúng
Điểm: 0/1.
Question 18
Điểm : 0/1

For large numbers of degrees of freedom, the critical χ2 values can be approximated as follows:

χ2 = (z + )2,

where k is the number of degrees of freedom and z is the critical value. To find the lower critical value, the negative z-value is used, to find the upper critical value, the positive z-value is used. Use this approximation to estimate the critical value of χ2 in a right-tailed hypothesis test with n =125 and α = 0.01.

Chọn một câu trả lời
 a. χ2 ≈ 162.833 b. χ2 ≈168.448 c. χ2 ≈ 163.981 d. χ2 ≈167.285
Không đúng
Điểm: 0/1.
Question 19
Điểm : 0/1
Which statement is true for the scores of 1, 2, 3, 4, 5, 5, 7, 8, 9, and 10?
Chọn một câu trả lời
 a. The mean is greater than the median. b. The mode is greater than the median. c. The median is greater than the mean. d. The mean is less than the mode.
Không đúng
Điểm: 0/1.
Question 20
Điểm : 0/1
Parking at a large university has become a very big problem. University administrators are interested in determining the average parking time (e.g. the time it takes a student to find a parking spot) of its students. An administrator inconspicuously followed 130 students and carefully recorded their parking times. Identify the sample of interest to the university administration.
Chọn một câu trả lời
 a. location of the parking spot b. parking time of a student c. parking times of the 130 students d. type of car (import or domestic)
Không đúng
Điểm: 0/1.
Question 21
Điểm : 0/1
The probability that a radish seed will germinate is 0.7. A gardener plants seeds in batches of 11. Find the standard deviation for the random variable X, the number of seeds germinating in each batch.
Chọn một câu trả lời
 a. 1.52 b. 1.25 c. 1.502 d. 2.77
Không đúng
Điểm: 0/1.
Question 22
Điểm : 0/1
The standard IQ test has a mean of 96 and a standard deviation of 14. We want to be 90% certain that we are within 4 IQ points of the true mean. Determine the required sample size.
Chọn một câu trả lời
 a. 130 b. 6 c. 1 d. 34
Không đúng
Điểm: 0/1.
Question 23
Điểm : 0/1
An archer is able to hit the bull's-eye 55% of the time. If she shoots 8 arrows, what is the probability that she gets exactly 4 bull's-eyes? Assume each shot is independent of the others.
Chọn một câu trả lời
 a. 0.2627 b. 0.0915 c. 0.0038 d. 0.1719
Không đúng
Điểm: 0/1.
Question 24
Điểm : 0/1
Let Z is a standard normal variable, find P(-0.73 < Z < 2.27).
Chọn một câu trả lời
 a. 0.7557 b. 1.54 c. 0.2211 d. 0.4884
Không đúng
Điểm: 0/1.
Question 25
Điểm : 0/1
The following table shows the political affiliation of voters in one city and their positions on stronger gun control laws.

 Favor Oppose Republican 0.09 0.26 Democrat 0.22 0.2 Other 0.11 0.12

What is the probability that a voter who favors stronger gun control laws is a Republican?
Chọn một câu trả lời
 a. 0.420 b. 0.786 c. 0.214 d. 0.257
Không đúng
Điểm: 0/1.
Question 26
Điểm : 0/1

Determine whether the hypothesis test involves a sampling distribution of means that is a normal distribution, Student t distribution, or neither.

Claim: μ = 959. Sample data: n = 25,$$\overline{x} = 951,$$ s = 25. The sample data appear to come from a normally distributed population with σ = 28.

Chọn một câu trả lời
 a. Normal b. Neither c. Student t
Không đúng
Điểm: 0/1.
Question 27
Điểm : 0/1

Suppose X is a uniform random variable over the interval [20, 90]. Find the probability that a randomly selected observation is between 23 and 85.

Chọn một câu trả lời
 a. 0.89 b. 0.5 c. 0.8 d. 0.11
Không đúng
Điểm: 0/1.
Question 28
Điểm : 0/1

Find the variance for the given probability distribution.

 x 0 1 2 3 4 P(x) 0.17 0.28 0.05 0.15 0.35

Chọn một câu trả lời
 a. 2.69 b. 7.43 c. 2.63 d. 2.46
Không đúng
Điểm: 0/1.
Question 29
Điểm : 0/1

A machine is set to pump cleanser into a process at the rate of 5 gallons per minute. Upon inspection, it is learned that the machine actually pumps cleanser at a rate described by the uniform distribution over the interval 4.5 to 7.5 gallons per minute. Find the probability that between 5.0 gallons and 6.0 gallons are pumped during a randomly selected minute.

Chọn một câu trả lời
 a. 1 b. 0 c. 0.67 d. 0.33
Không đúng
Điểm: 0/1.
Question 30
Điểm : 0/1
Construct the relative frequency distribution that corresponds to given frequency distribution
Chọn một câu trả lời
 a. b. c. d.
Không đúng
Điểm: 0/1.
Question 31
Điểm : 0/1
A new phone system was installed last year to help reduce the expense of personal calls that were being made by employees. Before the new system was installed, the amount being spent on personal calls follows a normal distribution with an average of $700 per month and a standard deviation of$50 per month. Refer to such expenses as PCE's (personal call expenses). Find the probability that a randomly selected month had a PCE that falls below $550. Chọn một câu trả lời  a. 0.2143 b. 0.9987 c. 0.7857 d. 0.0013 Không đúng Điểm: 0/1. Question 32 Điểm : 0/1 Find the probability that in 200 tosses of a fair six-sided die, a five will be obtained at least 40 times. Chọn một câu trả lời  a. 0.8810 b. 0.3875 c. 0.1210 d. 0.0871 Không đúng Điểm: 0/1. Question 33 Điểm : 0/1 The probability that a student at a certain college is male is 0.45. The probability that a student at that college has a job off campus is 0.33. The probability that a student at the college is male and has a job off campus is 0.15. If a student is chosen at random from the college, what is the probability that the student is male or has an off campus job? Chọn một câu trả lời  a. 0.37 b. 0.63 c. 0.47 d. 0.93 Không đúng Điểm: 0/1. Question 34 Điểm : 0/1 Find the critical value or values of $$\chi^2$$ based on the given information. H1: σ < 0.14 n = 23 α = 0.10 Chọn một câu trả lời  a. 14.042 b. 30.813 c. -30.813 d. 14.848 Không đúng Điểm: 0/1. Question 35 Điểm : 0/1 The probabilities that a customer entering a particular bookstore buys 0, 1, 2, 3, 4, or 5 books are 0.30, 0.20, 0.20, 0.15, 0.10, and 0.05 respectively. For the probability distribution above, find the variance. (Note: please give the answer as a real number accurate to 2 decimal places after the decimal point.) Đáp án : Không đúng Câu trả lời đúng: 2.31 Điểm: 0/1. Lịch sử của các câu trả lời #Thực hiệnĐáp ánTimeRaw scoreĐiểm 1Điểm22:02:23 on 3/04/1100 2Close&Grade22:02:57 on 3/04/1100 Question 36 Điểm : 0/1 The time between customer arrivals at a furniture store has an approximate exponential distribution with mean of 8.5 minutes. If a customer just arrived, find the probability that the next customer will not arrive for at least 20 minutes. Chọn một câu trả lời  a. 0.346230 b. 0.095089 c. 0.904911 d. 0.653770 Không đúng Điểm: 0/1. Question 37 Điểm : 0/1 A psychologist claims that more than 75 percent of the population suffers from professional problems due to extreme shyness. Assuming that a hypothesis test of the claim has been conducted and that the conclusion is failure to reject the null hypothesis, state the conclusion in nontechnical terms. Chọn một câu trả lời  a. There is not sufficient evidence to support the claim that the true proportion is less than 75 percent. b. There is not sufficient evidence to support the claim that the true proportion is greater than 75 percent. c. There is sufficient evidence to support the claim that the true proportion is greater than 75 percent. d. There is sufficient evidence to support the claim that the true proportion is less than 75 percent. Không đúng Điểm: 0/1. Question 38 Điểm : 0/1 An experiment consists of randomly choosing a number between 1 and 10. Let E be the event that the number chosen is even. List the sample points in E. Chọn một câu trả lời  a. {1, 3, 5, 7, 9} b. {5} c. {2, 4, 6, 8, 10} d. {1, 2, 3, 4, 5, 6, 7, 8, 9, 10} Không đúng Điểm: 0/1. Question 39 Điểm : 0/1 When conducting a t test for the correlation coefficient in a study with 16 individuals, the degrees of freedom will be Chọn một câu trả lời  a. 30. b. 31. c. 15. d. 14. Không đúng Điểm: 0/1. Question 40 Điểm : 0/1 Suppose that $$X$$ is a negative binomial random variable with $$p = 0.2$$ and $$r = 4$$. Determine $$P(X=20)$$. Chọn một câu trả lời  a. 0.0436 b. 0.9823 c. 0.0321 d. 0.9538 Không đúng Điểm: 0/1. Question 41 Điểm : 0/1 Many people think that a national lobby's successful fight against gun control legislation is reflecting the will of a minority of Americans. A previous random sample of 4000 citizens yielded 2250 who are in favor of gun control legislation. How many citizens would need to be sampled if a 95% confidence interval was desired to estimate the true proportion to within 5%? Chọn một câu trả lời  a. 379 b. 400 c. 385 d. 354 Không đúng Điểm: 0/1. Question 42 Điểm : 0/1 Let X represent the amount of time it takes a student to park in the library parking lot at the university. If we know that the distribution of parking times can be modeled using an exponential distribution with a mean of 4 minutes, find the probability that it will take a randomly selected student between 2 and 12 minutes to park in the library lot. Chọn một câu trả lời  a. 0.049787 b. 0.656318 c. 0.606531 d. 0.556744 Không đúng Điểm: 0/1. Question 43 Điểm : 0/1 A local bank needs information concerning the checking account balances of its customers. A random sample of 15 accounts was checked. The mean balance was$686.75 with a standard deviation of $256.20. Find a 98% confidence interval for the true mean. Assume that the account balances are normally distributed. Chọn một câu trả lời  a. ($487.31, $563.80) b. ($238.23, $326.41) c. ($326.21, $437.90) d. ($513.17, $860.33) Không đúng Điểm: 0/1. Question 44 Điểm : 0/1 A basketball player has made 70% of his foul shots during the season. If he shoots 3 foul shots in tonight's game, what is the probability that he makes all of the shots? Chọn một câu trả lời  a. 0.09 b. 0.343 c. 0.21 d. 0.686 Không đúng Điểm: 0/1. Question 45 Điểm : 0/1 Let X be a uniform random variable over the interval [0.1, 5] . What is the probability that the random variable X has a value less than 2.1? Chọn một câu trả lời  a. 0.3875 b. 0.0125 c. 0.6897 d. 0.1375 Không đúng Điểm: 0/1. Question 46 Điểm : 0/1 When considering area under the standard normal curve, decide whether the area to the left of z =0.2 is bigger than, smaller than, or equal to the area to the right of z = -0.2 Chọn một câu trả lời  a. bigger than b. smaller than c. equal to Không đúng Điểm: 0/1. Question 47 Điểm : 0/1 A machine is set to pump cleanser into a process at the rate of 10 gallons per minute. Upon inspection, it is learned that the machine actually pumps cleanser at a rate described by the uniform distribution over the interval 9.5 to 11.5 gallons per minute. What is the probability that at the time the machine is checked it is pumping more than 10.5 gallons per minute? Chọn một câu trả lời  a. 0.50 b. 0.7692 c. 0.667 d. 0.25 Không đúng Điểm: 0/1. Question 48 Điểm : 0/1 Find the mode(s) for the given dample data 98, 25, 98, 13, 25, 29, 56, 98 Chọn một câu trả lời  a. 55.3 b. 25 c. 42.5 d. 98 Không đúng Điểm: 0/1. Question 49 Điểm : 0/1 If you were constructing a 99% confidence interval of the normal population mean based on a sample of $$n = 25$$ where the standard deviation of the sample $$s = 0.05$$. What is the critical value? Let $$t_{0.005,24}=2.7969;t_{0.01,24}=2.4922;z_{0.01}=2.33; z_{0.05}=2.58$$. Chọn một câu trả lời  a. 2.7969 b. 2.4922 c. 2.7874 d. 2.4851 Không đúng Điểm: 0/1. Question 50 Điểm : 0/1 One year, professional sports players salaries averaged$1.5 million with a standard deviation of $0.7 million. Suppose a sample of 100 major league players was taken. Find the approximate probability that the average salary of the 100 players exceeded$1.1 million.

Chọn một câu trả lời
 a. approximately 0 b. 0.7357 c. 0.2357 d. approximately 1
Không đúng
Điểm: 0/1.
Question 51
Điểm : 0/1
A random number generator is set top generate integer random numbers between 1 and 10 inclusive following a uniform distribution. What is the probability of the random number generator generating a 7?
Chọn một câu trả lời
 a. 0.07 b. 0 c. 1/10 d. 1/2
Không đúng
Điểm: 0/1.
Question 52
Điểm : 0/1
The probability is 0.7 that a person shopping at a certain store will spend less than $20. For random samples of 28 customers, find the mean number of shoppers who spend less than$20.
Chọn một câu trả lời
 a. 6.0 b. 18.2 c. 19.6 d. 14.0
Không đúng
Điểm: 0/1.
Question 53
Điểm : 0/1
According to a college survey, 22% of all students work full time. Find the standard deviation for the random variable X, the number of students who work full time in samples of size 16.
Chọn một câu trả lời
 a. 3.52 b. 1.66 c. 1.88 d. 1.98
Không đúng
Điểm: 0/1.
Question 54
Điểm : 0/1
Construct the cumulative frequency distribution that coressponds to the given frequency distribution
Chọn một câu trả lời
 a. b. c. d.
Không đúng
Điểm: 0/1.
Question 55
Điểm : 0/1
A multiple choice test has 10 questions each of which has 4 possible answers, only one of which is correct. If Judy, who forgot to study for the test, guesses on all questions, what is the probability that she will answer exactly 3 questions correctly?
Chọn một câu trả lời
 a. 0.2503 b. 0.0021 c. 0.0156 d. 0.5006
Không đúng
Điểm: 0/1.
Question 56
Điểm : 0/1

A normal distribution has mean μ = 60 and standard deviation = 6, find the area under the curve  to the right of 64.

Chọn một câu trả lời
 a. 0.2535 b. 0.3525 c. 0.3535 d. 0.2525
Không đúng
Điểm: 0/1.
Question 57
Điểm : 0/1

In a sample of 10 randomly selected women, it was found that their mean height was 63.4 inches. From previous studies, it is assumed that the standard deviation, $$\sigma,$$ is 2.4. Construct the 95% confidence interval for the population mean.

Chọn một câu trả lời
 a. (58.1, 67.3) b. (61.9, 64.9) c. (60.8, 65.4) d. (59.7, 66.5)
Không đúng
Điểm: 0/1.
Question 58
Điểm : 0/1
The collection and summarization of the socioeconomic and physical characteristics of the employees of a particular firm is an example of
Chọn một câu trả lời
 a. descriptive statistics. b. a parameter. c. inferential statistics. d. a statistic.
Không đúng
Điểm: 0/1.
Question 59
Điểm : 0/1
A nurse at a local hospital is interested in estimating the birth weight of infants. How large a sample must she select if she desires to be 90% confident that the true mean is within 4 ounces of the sample mean? The standard deviation of the birth weights is known to be 6 ounces.
Chọn một câu trả lời
 a. 2 b. 6 c. 7 d. 3
Không đúng
Điểm: 0/1.
Question 60
Điểm : 0/1
Police estimate that 25% of drivers drive without their seat belts. If they stop 6 drivers at random, find the probability that all of them are wearing their seat belts.
Chọn một câu trả lời
 a. 0.178 b. 0.15 c. 0.0002 d. 0.45
Không đúng
Điểm: 0/1.
Question 61
Điểm : 0/1
Let Z is a standard normal variable, find the the probability that Z lies between 0 and 3.01.
Chọn một câu trả lời
 a. 0.4987 b. 0.1217 c. 0.9987 d. 0.5013
Không đúng
Điểm: 0/1.
Question 62
Điểm : 0/1

A cereal company claims that the mean weight of the cereal in its packets is at least 14 oz. Express the null hypothesis H0 and the alternative hypothesis H1 in symbolic form.

Chọn một câu trả lời
 a. H0: μ > 14H1: μ ≤ 14 b. H0: μ = 14H1: μ < 14 c. H0:μ = 14H1: μ > 14 d. H0: μ < 14H1: μ ≥ 14
Không đúng
Điểm: 0/1.
Question 63
Điểm : 0/1
A business venture can result in the following outcomes (with their corresponding chance of occurring in parentheses) Highly Successful (10%), Successful (25%), Break Even (25%), Disappointing (20%), and Highly Disappointing (?). If these are the only outcomes possible for the business venture, what is the chance that the business venture will be considered Highly Disappointing?
Chọn một câu trả lời
 a. 20% b. 10% c. 15% d. 25%
Không đúng
Điểm: 0/1.
Question 64
Điểm : 0/1

A researcher claims that 62% of voters favor gun control. Assume that a hypothesis test of the given claim will be conducted. Identify the type II error for the test.

Chọn một câu trả lời
 a. The error of rejecting the claim that the proportion favoring gun control is 62% when it really is less than 62%. b. The error of rejecting the claim that the proportion favoring gun control is more than 62% when it really is more than 62%. c. The error of failing to reject the claim that the proportion favoring gun control is 62% when it is actually different than 62%.
Không đúng
Điểm: 0/1.
Question 65
Điểm : 0/1

An employee at the local ice cream parlor asks three customers if they like chocolate ice cream. What is the population?

Chọn một câu trả lời
 a. three selected custermers b. all women custormers c. all men custormers d. all custormers
Không đúng
Điểm: 0/1.
Question 66
Điểm : 0/1
A new phone system was installed last year to help reduce the expense of personal calls that were being made by employees. Before the new system was installed, the amount being spent on personal calls followed a normal distribution with an average of $900 per month and a standard deviation of$50 per month. Refer to such expenses as PCE's (personal call expenses). Using the distribution above, what is the probability that a randomly selected month had a PCE of between $775.00 and$990.00?
Chọn một câu trả lời
 a. .0001 b. .9999 c. .9579 d. .0421
Không đúng
Điểm: 0/1.
Question 67
Điểm : 0/1
For a standard normal distribution, find the percentage of data that are more than 1 standard deviation away from the mean.
Chọn một câu trả lời
 a. 15.87% b. 34.13% c. 31.74% d. 68.26%
Không đúng
Điểm: 0/1.
Question 68
Điểm : 0/1
In a random sample of 60 computers, the mean repair cost was $150 with a population standard deviation of$36. Construct a 99% confidence interval for the population mean.
Chọn một câu trả lời
 a. ($238,$274) b. ($138,$162) c. ($537,$654) d. ($18,$54)
Không đúng
Điểm: 0/1.
Question 69
Điểm : 0/1

Let $$\overline{X}$$ denote the sample mean of a random sample of size n1 = 16 taken from a normal distribution $$N(\mu, 36),$$ and let $$\overline{Y}$$ denote the sample mean of a random sample of size n2 = 25 taken from a different normal distribution $$N(\mu, 9).$$ Compute $$P(\overline{X} - \overline{Y}>5).$$

Chọn một câu trả lời
 a. 1 b. 0 c. 0.999 d. 0.001
Không đúng
Điểm: 0/1.
Question 70
Điểm : 0/1

Construct a 99% confidence interval for the population mean, μ. Assume the population has a normal distribution. A group of 19 randomly selected students has a mean age of 22.4 years with a standard deviation of 3.8 years.

Chọn một câu trả lời
 a. (16.3, 26.9) b. (18.7, 24.1) c. (17.2, 23.6) d. (19.9, 24.9)
Không đúng
Điểm: 0/1.
Question 71
Điểm : 0/1
The claim is that the proportion of drowning deaths of children attributable to beaches is more than 0.25, and the sample statistics include n= 647 drowning deaths of children with 30% of them attributable to beaches. Find the value of the test statistic z using $$z=\frac{\overline{p}-p_0}{\sqrt{\frac{p_0(1-p_0)}{n}}}$$.
Chọn một câu trả lời
 a. 2.78 b. -2.78 c. -2.94 d. 2.94
Không đúng
Điểm: 0/1.
Question 72
Điểm : 0/1
The systolic blood pressure of 18-year-old women is normally distributed with a mean of 120 mmHg and a standard deviation of 12 mmHg. What percentage of 18-year-old women have a systolic blood pressure that lies within 3 standard deviations of the mean?
Chọn một câu trả lời
 a. 68% b. 95.% c. 99.7% d. 99.99%
Không đúng
Điểm: 0/1.
Question 73
Điểm : 0/1
In one region, the September energy consumption levels for single-family homes are normally distributed with a mean of 1050 kWh and a standard deviation of 218 kWh. For a randomly selected home, find the probability that the September energy consumption level is between 1100 kWh and 1225 kWh.
Chọn một câu trả lời
 a. 0.2881 b. 0.0910 c. 0.1971 d. 0.3791
Không đúng
Điểm: 0/1.
Question 74
Điểm : 0/1
A confidence interval was used to estimate the proportion of statistics students that are female. A random sample of 72 statistics students generated the following confidence interval: Using the information above, what size sample would be necessary if we wanted to estimate the true proportion to within 2% using 99% reliability?
Chọn một câu trả lời
 a. 4310 b. 3979 c. 4118 d. 4145
Không đúng
Điểm: 0/1.
Question 75
Điểm : 0/1

The principal of a middle school claims that test scores of the seventh-graders at his school vary less than the test scores of the seventh-graders at a neighboring school, which have variation described by σ = 14.7. Assuming that a hypothesis test of the claim has been conducted and that the conclusion is to reject the null hypothesis, state the conclusion in nontechnical terms.

Chọn một câu trả lời
 a. There is not sufficient evidence to support the claim that the standard deviation is less than 14.7. b. There is sufficient evidence to support the claim that the standard deviation is greater than 14.7. c. There is sufficient evidence to support the claim that the standard deviation is less than 14.7. d. There is not sufficient evidence to support the claim that the standard deviation is greater than 14.7.
Không đúng
Điểm: 0/1.
Question 76
Điểm : 0/1

Suppose x is a uniform random variable over the interval [40, 50]. Find the probability that a randomly selected observation exceeds 43.

Chọn một câu trả lời
 a. 0.9 b. 0.7 c. 0.1 d. 0.3
Không đúng
Điểm: 0/1.
Question 77
Điểm : 0/1

The mean replacement time for a random sample of 12 microwave ovens is 8.6 years with a standard deviation of 2.7 years. Construct the 98% confidence interval for the population variance, $$\sigma^2.$$ Assume the data are normally distributed

Chọn một câu trả lời
 a. (3.2, 26.3) b. (3.1, 22.5) c. (1.2, 9.7) d. (1.8, 5.1)
Không đúng
Điểm: 0/1.
Question 78
Điểm : 0/1

The number of ounces of soda that a vending machine dispenses per cup is normally distributed with a mean of 12 ounces and a standard deviation of 4 ounces. Find the number of ounces above which 80% of the dispensed sodas will fall.

Chọn một câu trả lời
 a. 12.4 b. 9.1 c. 8.6 d. 34.2
Không đúng
Điểm: 0/1.
Question 79
Điểm : 0/1

Carter Motor Company claims that its new sedan, the Libra, will average better than 30 miles per gallon in the city. Use μ, the true average mileage of the Libra. Express the null hypothesis H0 and the alternative hypothesis H1 in symbolic form.

Chọn một câu trả lời
 a. H0: μ < 30H1:μ ≥ 30 b. H0: μ = 30H1: μ > 30 c. H0: μ = 30H1: μ < 30 d. H0: μ > 30H1:μ ≤ 30
Không đúng
Điểm: 0/1.
Question 80
Điểm : 0/1
Which of the following is not true about the standard normal distribution?
Chọn một câu trả lời
 a. The total area under the standard normal curve is 1. b. The area under the standard normal curve to the left of z = 0 is negative. c. The standard normal curve is symmetric about 0. d. About 68% of its observations fall between -1 and 1.
Không đúng
Điểm: 0/1.
Question 81
Điểm : 0/1

It has been found that 40% of the employees who complete a sequence of executive seminars go on to become vice presidents. Assume that 10 graduates of the program are randomly selected, find the probability that at least two become vice presidents.

(Note: please give the answer as a real number accurate to 4 decimal places after the decimal point.)

Đáp án :
Không đúng
Câu trả lời đúng: 0.9536
Điểm: 0/1.
Lịch sử của các câu trả lời
#Thực hiệnĐáp ánTimeRaw scoreĐiểm
1Điểm22:02:23 on 3/04/1100
Question 82
Điểm : 0/1
Suppose that on a particular multiple choice question, 96% of the students answered correctly. What is the probability that a randomly selected student answered the question incorrectly?
Chọn một câu trả lời
 a. 0.96 b. 0.04 c. 0.48 d. 0.14
Không đúng
Điểm: 0/1.
Question 83
Điểm : 0/1
The volumes of soda in quart soda bottles are normally distributed with a mean of 32.3 oz and a standard deviation of 1.2 oz. What is the probability that the volume of soda in a randomly selected bottle will be less than 32 oz?
Chọn một câu trả lời
 a. 0.8026 b. 0.5987 c. 0.3821 d. 0.4013
Không đúng
Điểm: 0/1.
Question 84
Điểm : 0/1

Both Fred and Ed have a bag of candy containing a lemon drop, a cherry drop, and a lollipop. Each takes out a piece and eats it. What are the possible pairs of candies eaten?

Create the sample space of possible outcomes.

Chọn một câu trả lời
 a. LD-LD CD-LD LP-LP LD-LP CD-CD LD-LP LP-CD b. LD-LD CD-LD LP-LP LD-CD CD-CD LD-LP LP-CD c. CD-LD LD-LP LP-CD LP-LP LD-LD d. LD-CD LD-CD LD-CD LD-LP LD-LP LD-LP CD-LP
Không đúng
Điểm: 0/1.
Question 85
Điểm : 0/1
Using Excel to find three quartiles for the given data below:
1,  3,  6,  10,  15,  21,  28,  36.
Chọn một câu trả lời
 a. 4.5,  12.5,  24.5 b. 5.25,  12.5,  22.75 c. 4.5,  12.5,  22.75 d. 5.25,  12.5,  24.5
Không đúng
Điểm: 0/1.
Question 86
Điểm : 0/1
If the probability of a newborn child being female is 0.5, find the probability that in 100 births, 55 or more will be female.
Chọn một câu trả lời
 a. 0.8159 b. 0.1841 c. 0.0606 d. 0.7967
Không đúng
Điểm: 0/1.
Question 87
Điểm : 0/1
Assume that a procedure yields a binomial distribution with a trial repeated n times. Use the binomial probability formula to find the probability of x successes given the probability p of success on a single trial.

n =12, x = 5, p = 0.25
Chọn một câu trả lời
 a. 0.082 b. 0.091 c. 0.027 d. 0.103
Không đúng
Điểm: 0/1.
Question 88
Điểm : 0/1
A random sample of 10 parking meters in a beach community showed the following incomes for a day. Assume the incomes are normally distributed.

$3.60$4.50 $2.80$6.30 $2.60$5.20 $6.75$4.25 $8.00$3.00

Find the 95% confidence interval for the true mean.
Chọn một câu trả lời
 a. ($1.35,$2.85) b. ($3.39,$6.01) c. ($2.11,$5.34) d. ($4.81,$6.31)
Không đúng
Điểm: 0/1.
Question 89
Điểm : 0/1

Suppose a 95% confidence interval for μ turns out to be (1000, 2100). Give a definition of what it means to be "95% confident" in an inference.

Chọn một câu trả lời
 a. 95% of the observations in the sample fall in the given interval. b. In repeated sampling, the population parameter would fall in the given interval 95% of the time. c. In repeated sampling, 95% of the intervals constructed would contain the population mean. d. 95% of the observations in the entire population fall in the given interval.
Không đúng
Điểm: 0/1.
Question 90
Điểm : 0/1
For the sample below, find the number of observations that are within 1.5 standard deviations of the mean.
2,  3,  5,  5,  6,  3,  6,  5,  6,  9,  2,  5,  3,  5,  6,  3,  5,  6,  6,  9.
Chọn một câu trả lời
 a. 18 b. 17 c. 15 d. 16
Không đúng
Điểm: 0/1.
Question 91
Điểm : 0/1
Use the given information to find the P-value.

The test statistic in a right-tailed test is z = 1.43.
Chọn một câu trả lời
 a. 0.0434 b. 0.4236 c. 0.0764 d. 0.5000
Không đúng
Điểm: 0/1.
Question 92
Điểm : 0/1
On a multiple choice test with 16 questions, each question has four possible answers, one of which is correct. For students who guess at all answers, find the standard deviation for the random variable X, the number of correct answers.
Chọn một câu trả lời
 a. 1.746 b. 2 c. 1.732 d. 1.677
Không đúng
Điểm: 0/1.
Question 93
Điểm : 0/1
The grade point averages for 10 randomly selected students in a statistics class with 125 students are listed below.

2.0 3.2 1.8 2.9 0.9 4.0 3.3 2.9 3.6 0.8

What is the effect on the width of the confidence interval if the sample size is increased to 20?
Chọn một câu trả lời
 a. It is impossible to tell without more information. b. The width decreases. c. The width increases. d. The width remains the same.
Không đúng
Điểm: 0/1.
Question 94
Điểm : 0/1
A percentage distribution is given below for the size of families in one U.S. city.
 Size Percentage 2 42.8 3 21.1 4 19.2 5 11.6 6 3.3 7+ 2.0

A family is selected at random. Find the probability that the size of the family is 4 or more. Round your result to three decimal places.
Chọn một câu trả lời
 a. 0.192 b. 0.808 c. 0.169 d. 0.361
Không đúng
Điểm: 0/1.
Question 95
Điểm : 0/1

Which of the following is true about the sampling distribution of the sample mean?

Chọn một câu trả lời
 a. The mean of the sampling distribution is always μ. b. The shape of the sampling distribution is always approximately normal. c. The standard deviation of the sampling distribution is always σ. d. All of them are true.
Không đúng
Điểm: 0/1.
Question 96
Điểm : 0/1

Construct a 95% confidence interval for the population mean, μ. Assume the population has a normal distribution. A random sample of 16 fluorescent light bulbs has a mean life of 645 hours with a standard deviation of 31 hours.

Chọn một câu trả lời
 a. (876.2, 981.5) b. (321.7, 365.8) c. (628.5, 661.5) d. (531.2, 612.9)
Không đúng
Điểm: 0/1.
Question 97
Điểm : 0/1

Survey responses of nationalities of survey respondents. which type of data is?

Chọn một câu trả lời
 a. Nomial b. Ordinal c. Ratio d. Interval
Không đúng
Điểm: 0/1.
Question 98
Điểm : 0/1
For a standard normal distribution, find the percentage of data that are between 3 standard deviations below the mean and 1 standard deviation above the mean.
Chọn một câu trả lời
 a. 15.74% b. 16.00% c. 99.74% d. 84.00%
Không đúng
Điểm: 0/1.
Question 99
Điểm : 0/1
Assume that a procedure yields a binomial distribution with a trial repeated n times. Use the binomial probability formula to find the probability of x successes given the probability p of success on a single trial.

n = 4, x = 3, p = 1/6
Chọn một câu trả lời
 a. 0.0154 b. 0.0231 c. 0.0039 d. 0.0116
Không đúng
Điểm: 0/1.
Question 100
Điểm : 0/1
Use the given information to find the P-value.

The test statistic in a left-tailed test is z = -1.83.
Chọn một câu trả lời
 a. 0.4326 b. 0.4232 c. 0.0336 d. 0.0443
Không đúng
Điểm: 0/1.
Question 101
Điểm : 0/1
Assume that z scores are normally distributed with a mean of 0 and a standard deviation of 1. If P(Z > c) = 0.1093, find c.
Chọn một câu trả lời
 a. 0.4562 b. 0.27 c. -1.23 d. 1.23
Không đúng
Điểm: 0/1.
Question 102
Điểm : 0/1

The accompanying table shows the probability distribution for x, the number that shows up when a loaded die is rolled. Find the variance for the probability distribution.

 x 1 2 3 4 5 6 P(x) 0.16 0.19 0.22 0.21 0.12 0.1

Chọn một câu trả lời
 a. 9.62 b. 12.86 c. 2.36 d. 2.03
Không đúng
Điểm: 0/1.
Question 103
Điểm : 0/1

The owner of a football team claims that the average attendance at games is over 67,800, and he is therefore justified in moving the team to a city with a larger stadium. Express the null hypothesis H0 and the alternative hypothesis H1 in symbolic form.

Chọn một câu trả lời
 a. H0: μ, the average attendance at games, is equal to 67,800 H1: μ, the average attendance at games, is less than 67,800 b. H0: μ, the average attendance at games, is less than 67,800H1: μ, the average attendance at games, is greater than or equal to 67,800 c. H0: μ, the average attendance at games, is equal to 67,800H1: μ, the average attendance at games, is greater than 67,800 d. H0: μ, the average attendance at games, is greater than 67,800H1: μ, the average attendance at games, is less than or equal to 67,800
Không đúng
Điểm: 0/1.
Question 104
Điểm : 0/1

The manufacturer of a refrigerator system for beer kegs produces refrigerators that are supposed to maintain a true mean temperature, μ, of 50°F, ideal for a certain type of German pilsner. The owner of the brewery does not agree with the refrigerator manufacturer, and claims he can prove that the true mean temperature is incorrect. Assume that a hypothesis test of the given claim will be conducted. Identify the type I error for the test.

Chọn một câu trả lời
 a. The error of rejecting the claim that the mean temperature equals 50°F when it is really different from 50°F. b. The error of failing to reject the claim that the mean temperature equals 50°F when it is really different from 50°F. c. The error of rejecting the claim that the mean temperature equals 50°F when it really does equal 50°F.
Không đúng
Điểm: 0/1.
Question 105
Điểm : 0/1
A campus program evenly enrolls undergraduate and graduate students. If a random sample of 4 students is selected from the program to be interviewed about the introduction of a new fast food outlet on the ground floor of the campus building, what is the probability that all 4 students selected are undergraduate students?
Chọn một câu trả lời
 a. 0.0625 b. 0.0256 c. 1.00 d. 0.16
Không đúng
Điểm: 0/1.
Question 106
Điểm : 0/1

Flip a coin twice, create the sample space of possible outcomes.

Chọn một câu trả lời
 a. HH HT TH TT b. HH HT TT c. HH TT HT HT d. HT TH
Không đúng
Điểm: 0/1.
Question 107
Điểm : 0/1
The number of power outages at a nuclear power plant has a Poisson distribution with a mean of 6 outages per year. The probability that there will be exactly 3 power outages in a year is
Chọn một câu trả lời
 a. 0.4829 b. 0.0892 c. 0.8102 d. 0.4291
Không đúng
Điểm: 0/1.
Question 108
Điểm : 0/1
If two balanced die are rolled, the possible outcomes can be represented as follows.

(1, 1) (2, 1) (3, 1) (4, 1) (5, 1) (6, 1)
(1, 2) (2, 2) (3, 2) (4, 2) (5, 2) (6, 2)
(1, 3) (2, 3) (3, 3) (4, 3) (5, 3) (6, 3)
(1, 4) (2, 4) (3, 4) (4, 4) (5, 4) (6, 4)
(1, 5) (2, 5) (3, 5) (4, 5) (5, 5) (6, 5)
(1, 6) (2, 6) (3, 6) (4, 6) (5, 6) (6, 6)

Determine the probability that the sum of the dice is 7.
Chọn một câu trả lời
 a. 5/36 b. 3/12 c. 1/6 d. 2/9
Không đúng
Điểm: 0/1.
Question 109
Điểm : 0/1
A company has 2 machines that produce widgets. An older machine produces 23% defective widgets, while the new machine produces only 8% defective widgets. In addition, the new machine produces 3 times as many widgets as the older machine does. Given that a widget was produced by the new machine, what is the probability it is not defective?
Chọn một câu trả lời
 a. 0.50 b. 0.94 c. 0.06 d. 0.92
Không đúng
Điểm: 0/1.
Question 110
Điểm : 0/1
At one college, GPAs are normally distributed with a mean of 2.6 and a standard deviation of 0.4. What percentage of students at the college have a GPA between 2.2 and 3?
Chọn một câu trả lời
 a. 89% b. 99.7% c. 68% d. 84.13%
Không đúng
Điểm: 0/1.
Question 111
Điểm : 0/1
When is the correlation coefficient zero?
Chọn một câu trả lời
 a. when there is no linear correlation b. when there is a perfect positive linear correlation c. It is never zero. d. when there is a perfect negative linear correlation
Không đúng
Điểm: 0/1.
Question 112
Điểm : 0/1
For sample sizes greater than 40, the sampling distribution of the mean will be approximately normally distributed
Chọn một câu trả lời
 a. only if the shape of the population is symmetrical. b. only if the population is normally distributed. c. only if the standard deviation of the samples are known. d. regardless of the shape of the population.
Không đúng
Điểm: 0/1.
Question 113
Điểm : 0/1

Find the critical value or values of $$\chi^2$$ based on the given information.

H1: σ > 26.1
n = 9
α = 0.01

Chọn một câu trả lời
 a. 21.666 b. 2.088 c. 20.090 d. 1.646
Không đúng
Điểm: 0/1.
Question 114
Điểm : 0/1

To determine the difference , if any, between two brands of radial tires, 12 tires of each brand are tested. Assume that the lifetimes of both brands of tires come from the same normal distribution $$N(\mu, 3300^2).$$ Compute $$P(\overline{X}-\overline{Y} <-2500).$$

Chọn một câu trả lời
 a. 0.0686 b. 0.0314 c. 0.6860 d. 0.3140
Không đúng
Điểm: 0/1.
Question 115
Điểm : 0/1
Find the mean of the following probability distribution.
 x 0 1 2 3 4 P(x) 0.19 0.37 0.16 0.26 0.02

Chọn một câu trả lời
 a. 1.64 b. 1.74 c. 1.55 d. 1.45
Không đúng
Điểm: 0/1.
Question 116
Điểm : 0/1
When considering area under the standard normal curve, decide whether the area to the right of z = 2 is bigger than, smaller than, or equal to the area to the right of z = 2.5.
Chọn một câu trả lời
 a. equal to b. smaller than c. bigger than
Không đúng
Điểm: 0/1.
Question 117
Điểm : 0/1
Find the percentile for the data point.

data set: 3  11  8  6  3  3  11  6  3  11  2  11  15  4  9  3  12  8  6  11
data point: 6
Chọn một câu trả lời
 a. 62 b. 35 c. 40 d. 25
Không đúng
Điểm: 0/1.
Question 118
Điểm : 0/1

Find the critical value or values of x2 based on the given information.

H0: σ = 8.0

n = 10

α = 0.01

Chọn một câu trả lời
 a. 23.209 b. 21.666 c. 2.088, 21.666 d. 1.735, 23.589
Không đúng
Điểm: 0/1.
Question 119
Điểm : 0/1

Construct a 90% confidence interval for the population mean, μ. Assume the population has a normal distribution. In a recent study of 22 eighth graders, the mean number of hours per week that they watched television was 19.6 with a standard deviation of 5.8 hours.

Chọn một câu trả lời
 a. (5.87, 7.98) b. (18.63, 20.89) c. (19.62, 23.12) d. (17.47, 21.73)
Không đúng
Điểm: 0/1.
Question 120
Điểm : 0/1

Let X be a random variable has the following uniform density function f(x) = 0.1 when 0< x < 10. What is the probability that the random variable X has a value greater than 5.3?

Chọn một câu trả lời
 a. 0.21 b. 0.47 c. 0.28 d. 0.49
Không đúng
Điểm: 0/1.
Question 121
Điểm : 0/1

Jared was working on a project to look at global warming and accessed an Internet site where he captured average global surface temperatures from 1866. Which of the four methods of data collection was he using?

Chọn một câu trả lời
 a. Observation b. Retrospective study c. Experimentation d. Surveying
Không đúng
Điểm: 0/1.
Question 122
Điểm : 0/1
If you were constructing a 99% confidence interval of the population mean based on a sample of n=25 where the standard deviation of the sample s = 0.05, the critical value of t will be
Chọn một câu trả lời
 a. 2.4922. b. 2.7969. c. 2.7874. d. 2.4851.
Không đúng
Điểm: 0/1.
Question 123
Điểm : 0/1

Suppose that P(A|B) = 0.3 and P(B) = 0.4. Determine P(A' and B).

Chọn một câu trả lời
 a. 0.28 b. 0.75 c. 0.35 d. 0.12
Không đúng
Điểm: 0/1.
Question 124
Điểm : 0/1
The diameter of ball bearings produced in a manufacturing process can be explained using a uniform distribution over the interval 4.5 to 6.5 millimeters. What is the probability that a randomly selected ball bearing has a diameter greater than 5.2 millimeters?
Chọn một câu trả lời
 a. 0.8 b. 2.5 c. 0.4727 d. 0.65
Không đúng
Điểm: 0/1.
Question 125
Điểm : 0/1
Suppose that $$X$$ has the probability density function $$f(x)=1.5x^2$$ for $$-1 Chọn một câu trả lời  a. 1 b. 2.35 c. 5.4 d. 0.125 Không đúng Điểm: 0/1. Question 126 Điểm : 0/1 Two white mice mate. The male has both a white and a black fur-color gene. The female has only white fur-color genes. The fur color of the offspring depends on the pairs of fur-color genes that they receive. Assume that neither the white nor the black gene dominates. List the possible outcomes. W = white and B = black Create the sample space of possible outcomes. Chọn một câu trả lời  a. WB, BW b. WW, BW c. WW, WW d. WW, BB Không đúng Điểm: 0/1. Question 127 Điểm : 0/1 The diameters of ball bearings produced in a manufacturing process can be described using a uniform distribution over the interval 8.5 to 10.5 millimeters. What is the probability that a randomly selected ball bearing has a diameter greater than 9.2 millimeters? Chọn một câu trả lời  a. 0.4842 b. 0.65 c. 0.8762 d. 4.5 Không đúng Điểm: 0/1. Question 128 Điểm : 0/1 A cereal company claims that the mean weight of the cereal in its packets is at least 14 oz. Assuming that a hypothesis test of the claim has been conducted and that the conclusion is to reject the null hypothesis, state the conclusion in nontechnical terms. Chọn một câu trả lời  a. There is not sufficient evidence to warrant rejection of the claim that the mean weight is less than b. There is sufficient evidence to warrant rejection of the claim that the mean weight is less than c. There is sufficient evidence to warrant rejection of the claim that the mean weight is at least d. There is not sufficient evidence to warrant rejection of the claim that the mean weight is at least Không đúng Điểm: 0/1. Question 129 Điểm : 0/1 Flip a coin three times, create the sample space of possible outcomes. Chọn một câu trả lời  a. HHH TTT THT HTH HHT TTH HTH b. HTT THT HTH HHH TTH TTT c. HHH HHT HTH HTT THH THT TTH TTT d. HHH HTT HTH TTT HTT THH HHT THT Không đúng Điểm: 0/1. Question 130 Điểm : 0/1 Find the standard deviation for the given probability distribution.  x 0 1 2 3 4 P(x) 0.37 0.05 0.13 0.25 0.2 Chọn một câu trả lời  a. 1.60 b. 2.56 c. 2.45 d. 1.71 Không đúng Điểm: 0/1. Question 131 Điểm : 0/1 The amount of corn chips dispensed into a 20-ounce bag by the dispensing machine has been identified at possessing a normal distribution with a mean of 20.5 ounces and a standard deviation of 0.2-ounce. Suppose 100 bags of chips were randomly selected from this dispensing machine. Find the probability that the sample mean weight of these 100 bags exceeded 20.6 ounces. Chọn một câu trả lời  a. approximately 0 b. 0.6915 c. 0.1915 d. 0.3085 Không đúng Điểm: 0/1. Question 132 Điểm : 0/1 The length of time it takes college students to find a parking spot in the library parking lot follows a normal distribution with a mean of 4.0 minutes and a standard deviation of 1 minute. Find the probability that a randomly selected college student will take between 2.5 and 5.0 minutes to find a parking spot in the library lot. Chọn một câu trả lời  a. 0.4938 b. 0.0919 c. 0.7745 d. 0.2255 Không đúng Điểm: 0/1. Question 133 Điểm : 0/1 A store manager kept track of the number of newspapers sold each week over a seven-week period. The results are shown below: 95, 38, 221, 122, 258, 237, 233. Find the median number of newspapers sold Chọn một câu trả lời  a. 172 b. 221 c. 122 d. 233 Không đúng Điểm: 0/1. Question 134 Điểm : 0/1 A psychologist claims that more than 3 percent of the population suffers from professional problems due to extreme shyness. Assume that a hypothesis test of the given claim will be conducted. Identify the type II error for the test. Chọn một câu trả lời  a. The error of rejecting the claim that the true proportion is at most 3 percent when it really is at most 3 percent. b. The error of failing to reject the claim that the true proportion is at most 3 percent when it is actually more than 3 percent. c. The error of rejecting the claim that the true proportion is more than 3 percent when it really is more than 3 percent. Không đúng Điểm: 0/1. Question 135 Điểm : 0/1 According to police sources a car with a certain protection system will be recovered 87% of the time. Find the probability that 4 of 7 stolen cars will be recovered. Chọn một câu trả lời  a. 0.044 b. 0.87 c. 0.571 d. 0.13 Không đúng Điểm: 0/1. Question 136 Điểm : 0/1 If X is a normal random variable with μ = 50 and σ = 6, then the probability that X is not between 44 and 56 is Chọn một câu trả lời  a. 0.8413. b. 0.6826. c. 0.3413. d. 0.3174. Không đúng Điểm: 0/1. Question 137 Điểm : 0/1 An entomologist writes an article in a scientific journal which claims that fewer than 16 in ten thousand male fireflies are unable to produce light due to a genetic mutation. Assume that a hypothesis test of the given claim will be conducted. Identify the type I error for the test. Chọn một câu trả lời  a. The error of rejecting the claim that the true proportion is at least 16 in ten thousand when it really is at least 16 in ten thousand. b. The error of failing to reject the claim that the true proportion is at least 16 in ten thousand when it is actually less than 16 in ten thousand. c. The error of rejecting the claim that the true proportion is less than 16 in ten thousand when it really is less than 16 in ten thousand. Không đúng Điểm: 0/1. Question 138 Điểm : 0/1 Those methods involving the collection, presentation, and characterization of a set of data in order to properly describe the various features of that set of data are called Chọn một câu trả lời  a. the scientific method. b. sampling. c. descriptive statistics. d. statistical inference. Không đúng Điểm: 0/1. Question 139 Điểm : 0/1 The following table shows the political affiliation of voters in one city and their positions on stronger gun control laws.  Favor Oppose Republican 0.11 0.27 Democrat 0.25 0.16 Other 0.15 0.06 What is the probability that a Democrat opposes stronger gun control laws? Chọn một câu trả lời  a. 0.390 b. 0.490 c. 0.160 d. 0.327 Không đúng Điểm: 0/1. Question 140 Điểm : 0/1 The distances traveled (in miles) to 7 different swim meets are given below: 12, 18, 31, 46, 69, 71, 85. Find the median distance traveled. Chọn một câu trả lời  a. 47 miles b. 69 miles c. 31 miles d. 46 miles Không đúng Điểm: 0/1. Question 141 Điểm : 0/1 We have created a 95% confidence interval for$$\mu$$with the result (10, 15). What decision will we make if we test$$H_0: \mu =16$$versus$$H_1: \mu
eq 16$$at$$\alpha= 0.05$$? Chọn một câu trả lời  a. Accept$$H_0$$in favor of$$H_1$$. b. Reject$$H_0$$in favor of$$H_1$$. c. Fail to reject$$H_0$$in favor of$$H_1$$. d. We cannot tell what our decision will be from the information given. Không đúng Điểm: 0/1. Question 142 Điểm : 0/1 A researcher claims that 62% of voters favor gun control.Express the null hypothesis H0 and the alternative hypothesis H1 in symbolic form. Chọn một câu trả lời  a. H0: p ≠ 0.62H1: p = 0.62 b. H0: p = 0.62H1: p ≠ 0.62 c. H0: p < 0.62H1: p ≥ 0.62 d. H0: p ≥ 0.62H1: p < 0.62 Không đúng Điểm: 0/1. Question 143 Điểm : 0/1 In a binomial distribution with 10 trials, which of the following is true? Chọn một câu trả lời  a. P(x > 7) = P(x ≥ 8) b. P(3 ≤ x ≤ 5) = P(3 < x < 5) c. P(x < 6) = 1 - P(x ≥ 7) d. P(x < 4) = P(x ≥ 5) - P(x ≥ 4) Không đúng Điểm: 0/1. Question 144 Điểm : 0/1 If a random variable has the normal distribution with μ = 30 and σ = 5, find the probability that it will take on the value between 31 and 35. Chọn một câu trả lời  a. 0.362 b. 0.7624 c. 0.262 d. 0.3621 Không đúng Điểm: 0/1. Question 145 Điểm : 0/1 To determine the difference , if any, between two brands of radial tires, 12 tires of each brand are tested. Assume that the lifetimes of both brands of tires come from the same normal distribution N(m, 33002). The distribution of the difference of the sample mean$$\overline{X}$$-$$\overline{Y}.$$Chọn một câu trả lời  a. normal with mean 0 and standard deviation 1347.22 b. normal with mean 12 and variance 1347.22. c. normal with mean m and variance 1347.22. d. standard normal. Không đúng Điểm: 0/1. Question 146 Điểm : 0/1 Assume that the data has a normal distribution and the number of observations is greater than fifty. Find the critical z value used to test a null hypothesis. α = 0.05 for a two-tailed test. Chọn một câu trả lời  a. ±2.575 b. ±1.764 c. ±1.96 d. ±1.645 Không đúng Điểm: 0/1. Question 147 Điểm : 0/1 Assume that z scores are normally distributed with a mean of 0 and a standard deviation of 1. If P(-a < Z < a) = 0.4314, find a. Chọn một câu trả lời  a. 0.3328 b. 0.57 c. 1.49 d. -0.18 Không đúng Điểm: 0/1. Question 148 Điểm : 0/1 Suppose X is a uniform random variable over the interval [40, 70]. Find the standard deviation of X. Chọn một câu trả lời  a. 3.03 b. 8.66 c. 31.75 d. 1.58 Không đúng Điểm: 0/1. Question 149 Điểm : 0/1 Let X represent the amount of time it takes a student to park in the library parking lot at the university. If we know that the distribution of parking times can be modeled using an exponential distribution with a mean of 4 minutes, find the probability that it will take a randomly selected student more than 10 minutes to park in the library lot. Chọn một câu trả lời  a. 0.670320 b. 0.917915 c. 0.329680 d. 0.082085 Không đúng Điểm: 0/1. Question 150 Điểm : 0/1 If two balanced die are rolled, the possible outcomes can be represented as follows. (1, 1) (2, 1) (3, 1) (4, 1) (5, 1) (6, 1) (1, 2) (2, 2) (3, 2) (4, 2) (5, 2) (6, 2) (1, 3) (2, 3) (3, 3) (4, 3) (5, 3) (6, 3) (1, 4) (2, 4) (3, 4) (4, 4) (5, 4) (6, 4) (1, 5) (2, 5) (3, 5) (4, 5) (5, 5) (6, 5) (1, 6) (2, 6) (3, 6) (4, 6) (5, 6) (6, 6) Determine the probability that the sum of the dice is 4 or 12. Chọn một câu trả lời  a. 1/9 b. 5/9 c. 1/2 d. 7/36 Không đúng Điểm: 0/1. Question 151 Điểm : 0/1 According to the Center for Disease Control, 41.5% of babies born in the U.S. in 2004 were still being breastfed at 6 months of age. If 4 children who were born in the U.S. in 2004 are randomly selected, what is the probability that none of them were breastfed for at least 6 months? Chọn một câu trả lời  a. 0.12 b. 0.585 c. none of these d. 0.03 Không đúng Điểm: 0/1. Question 152 Điểm : 0/1 When considering area under the standard normal curve, decide whether the area between z = -1.5 and z = 1.1 is bigger than, smaller than, or equal to the area between z = -1.1 and z = 1.5. Chọn một câu trả lời  a. smaller than b. equal to c. bigger than Không đúng Điểm: 0/1. Question 153 Điểm : 0/1 A polltaker asked graduating college seniors how many times they had given blood in the last year. The results of the survey are given below. The random variable x represents the number of times a person gave blood and P(x) represents the probability of selecting a graduating college who had given blood that percent of the time. What is the standard deviation for the number of times a person gave blood based on this poll?  x 0 1 2 3 4 5 6 P(x) 0.3 0.25 0.2 0.12 0.07 0.04 0.02 Chọn một câu trả lời  a. 2.23 b. 1.82 c. 1.54 d. 1.16 Không đúng Điểm: 0/1. Question 154 Điểm : 0/1 Let$$X$$be uniformly distributed over [0, 1]. Calculate$$E[X^3]$$. Chọn một câu trả lời  a. 0.5 b. 0.25 c. 1.5 d. 3 Không đúng Điểm: 0/1. Question 155 Điểm : 0/1 The lifetimes of light bulbs of a particular type are normally distributed with a mean of 360 hours and a standard deviation of 5 hours. What percentage of the bulbs have lifetimes that lie within 1 standard deviation of the mean? Chọn một câu trả lời  a. 95% b. 31.74% c. 68% d. 84.13% Không đúng Điểm: 0/1. Question 156 Điểm : 0/1 The breakdown of workers in a particular state according to their political affiliation and type of job held is shown here. Suppose a worker is selected at random within the state and the worker's political affiliation and type of job are noted. Political Affiliation Given the worker is a Democrat, what is the probability that the worker is in a white collar job. Chọn một câu trả lời  a. 0.526 b. 0.303 c. 0.417 d. 0.576 Không đúng Điểm: 0/1. Question 157 Điểm : 0/1 The age distribution of students at a community college is given below.  Age (years) Number of students Under 21 409 21-24 404 25-28 276 29-32 155 33-36 97 37-40 63 Over 40 86 A student from the community college is selected at random. Find the probability that the student is 21 years or over. Give your answer as a decimal rounded to three decimal places. Chọn một câu trả lời  a. 0.274 b. 0.271 c. 0.729 d. 0.726 Không đúng Điểm: 0/1. Question 158 Điểm : 0/1 The lengths of human pregnancies are normally distributed with a mean of 268 days and a standard deviation of 15 days. What is the probability that a pregnancy lasts at least 300 days? Chọn một câu trả lời  a. 0.0179 b. 0.4834 c. 0.9834 d. 0.0166 Không đúng Điểm: 0/1. Question 159 Điểm : 0/1 The probability that a house in an urban area will be burglarized is 2%. If 29 houses are randomly selected, what is the probability that none of the houses will be burglarized? Chọn một câu trả lời  a. 0.557 b. 0.000 c. 0.020 d. 0.001 Không đúng Điểm: 0/1. Question 160 Điểm : 0/1 The diameters of pencils produced by a certain machine are normally distributed with a mean of 0.30 inches and a standard deviation of 0.01 inches. What is the probability that the diameter of a randomly selected pencil will be less than 0.285 inches? Chọn một câu trả lời  a. 0.0596 b. 0.9332 c. 0.1336 d. 0.0668 Không đúng Điểm: 0/1. Question 161 Điểm : 0/1 Based on the scores 1, 9, 3, 6, 1, 2, 6, 2, 2, and 8, a score of 4 is the Chọn một câu trả lời  a. mean. b. mode. c. median. d. standard deviation. Không đúng Điểm: 0/1. Question 162 Điểm : 0/1 Compute the critical value$$z_{\alpha/2}$$that corresponds to a 94% level of confidence. Chọn một câu trả lời  a. 1.96 b. 1.88 c. 1.645 d. 2.33 Không đúng Điểm: 0/1. Question 163 Điểm : 0/1 For two events A and B, P(A) = 0.8, P(B) = 0.2, and P(A and B) = 0.16. It follows that A and B are Chọn một câu trả lời  a. neither disjoint nor independent. b. independent but not disjoint. c. both disjoint and independent. d. disjoint but not independent. Không đúng Điểm: 0/1. Question 164 Điểm : 0/1 A test consists of 10 true/false questions. To pass the test a student must answer at least 7 questions correctly. If a student guesses on each question, what is the probability that the student will pass the test? Chọn một câu trả lời  a. 0.172 b. 0.055 c. 0.117 d. 0.945 Không đúng Điểm: 0/1. Question 165 Điểm : 0/1 Find the mean of the data summarized in the given frequency distribution.  Daily Low Temperature (F) Frequency 35-39 1 40-44 3 45-49 5 50-54 11 55-59 7 60-64 7 65-69 1 Chọn một câu trả lời  a. 55.1 b. 53.4 c. 47.9 d. 39.5 Không đúng Điểm: 0/1. Question 166 Điểm : 0/1 A machine is set to pump cleanser into a process at the rate of 10 gallons per minute. Upon inspection, it is learned that the machine actually pumps cleanser at a rate described by the uniform distribution over the interval 9.5 to 13.5 gallons per minute. Find the variance of the distribution. Chọn một câu trả lời  a. 44.08 b. 1.33 c. 8.33 d. 0.75 Không đúng Điểm: 0/1. Question 167 Điểm : 0/1 Friskie is having her fifth litter. The prior litters have either been three normal pups or two normal pups and a runt. Assume the probability of either outcome is 50%. Create the sample space of possible outcomes. Chọn một câu trả lời  a. N NN NR NNN NRN b. NR NNR NNR c. NNR NNN d. NNN RNN NR Không đúng Điểm: 0/1. Question 168 Điểm : 0/1 According to a survey of American households, the probability that the residents own 2 cars if annual household income is over 25,000 is 80%. Of the households surveyed, 60% had incomes over 25,000 and 70% had 2 cars. The probability that annual household income is over 25,000 if the residents of a household own 2 cars is: Chọn một câu trả lời  a. 0.42 b. 0.69 c. 0.48 d. 0.50 Không đúng Điểm: 0/1. Question 169 Điểm : 0/1 According to a survey of American households, the probability that the residents own 2 cars if annual household income is over 25,000 is 80%. Of the households surveyed, 60% had incomes over 25,000 and 70% had 2 cars. The probability that the residents of a household do not own 2 cars and have an income over 25,000 a year is: Chọn một câu trả lời  a. 0.22 b. 0.18 c. 0.12 d. 0.48 Không đúng Điểm: 0/1. Question 170 Điểm : 0/1 Assume that the heights of men are normally distributed. A random sample of 16 men have a mean height of 67.5 inches and a standard deviation of 3.2 inches. Construct a 99% confidence interval for the population standard deviation,$$\sigma.$$Chọn một câu trả lời  a. (1.2, 3.2) b. (2.2, 6.0) c. (2.2, 5.4) d. (2.2, 5.8) Không đúng Điểm: 0/1. Question 171 Điểm : 0/1 When considering area under the standard normal curve, decide whether the area between z = 3 and z = -3 is bigger than, smaller than, or equal to the area between z = 2.7 and z = 2.9. Chọn một câu trả lời  a. equal to b. smaller than c. bigger than Không đúng Điểm: 0/1. Question 172 Điểm : 0/1 Find the standard deviation for the binomial distribution which has the stated values of n and p. Round your answer to the nearest hundredth. n = 2661; p = 0.63 Chọn một câu trả lời  a. 28.18 b. 22.50 c. 29.03 d. 24.91 Không đúng Điểm: 0/1. Question 173 Điểm : 0/1 Survey responses of temperatures of the ocean at various depths. which type of data is? Chọn một câu trả lời  a. Interval b. Nomial c. Ratio d. Ordinal Không đúng Điểm: 0/1. Question 174 Điểm : 0/1 Let X be a uniform random variable over the interval [1, 9] . What is the probability that the random variable X has a value less than 6? Chọn một câu trả lời  a. 0.875 b. 0.500 c. 0.400 d. 0.625 Không đúng Điểm: 0/1. Question 175 Điểm : 0/1 Find the variance for the given sample data 53 52 75 62 68 58 49 49 Chọn một câu trả lời  a. 67.9 b. 8.2 c. 9.5 d. 89.6 Không đúng Điểm: 0/1. Question 176 Điểm : 0/1 At a computer manufacturing company, the actual size of computer chips is normally distributed with a mean of 1 centimeter and a standard deviation of 0.1 centimeter. A random sample of 12 computer chips is taken. What is the standard error for the sample mean? Chọn một câu trả lời  a. 0.029 b. 0.120 c. 0.050 d. 0.091 Không đúng Điểm: 0/1. Question 177 Điểm : 0/1 Find z if the normal curve area to the right of z is 0.8997. Chọn một câu trả lời  a. -2.2798 b. -3.2798 c. -1.2798 d. -4.2798 Không đúng Điểm: 0/1. Question 178 Điểm : 0/1 The heights of a group of professional basketball players are summarized in the frequency distribution below. Find the mean height. Round your answer to one decimal place. Chọn một câu trả lời  a. 76.4 b. 74.6 c. 78.2 d. 13.5 Không đúng Điểm: 0/1. Question 179 Điểm : 0/1 Assume that blood pressure readings are normally distributed with a mean of 124 and a standard deviation of 6.4. If 64 people are randomly selected, find the probability that their mean blood pressure will be less than 126. Chọn một câu trả lời  a. 0.8615 b. 0.0062 c. 0.9938 d. 0.2998 Không đúng Điểm: 0/1. Question 180 Điểm : 0/1 The probability of winning a certain lottery is 1/51949. For people who play 560 times, find the standard deviation for the random variable X, the number of wins. Chọn một câu trả lời  a. 0.0108 b. 0.1038 c. 0.1223 d. 0.1137 Không đúng Điểm: 0/1. Question 181 Điểm : 0/1 The mean diameter of marbles manufactured at a particular toy factory is 0.850 cm with a standard deviation of 0.010cm. What is the probability of selecting a random sample of 100 marbles that has a mean diameter greater than 0.851 cm? Chọn một câu trả lời  a. 0.8023 b. 0.1587 c. 0.5398 d. 0.8413 Không đúng Điểm: 0/1. Question 182 Điểm : 0/1 Suppose that a number of miles that a car can run before its battery wears out is exponentially distributed with an average value of 10000 miles. If a person desires to take a 5000-mile trip, what is the probability that she will be able to complete her trip without having to replace her car battery? Chọn một câu trả lời  a. 0.3 b. 0.7 c. 0.6 d. 0.5 Không đúng Điểm: 0/1. Question 183 Điểm : 0/1 The distribution of B.A. degrees conferred by a local college is listed below, by major.  Major Frequency Engineering 868 English 2073 Mathematics 2164 Chemistry 318 Physics 856 Liberal Arts 1358 Business 1676 What is the probability that a randomly selected degree is not in Mathematics? Chọn một câu trả lời  a. 0.697 b. 0.768 c. 0.303 d. 0.232 Không đúng Điểm: 0/1. Question 184 Điểm : 0/1 Assume that X has a normal distribution with the mean is μ = 15.2 and the standard deviation is σ = 0.9. Find the probability that X is between 14.3 and 16.1. Chọn một câu trả lời  a. 0.8413 b. 0.1587 c. 0.6826 d. 0.3413 Không đúng Điểm: 0/1. Question 185 Điểm : 0/1 Let Z is a standard normal variable, find the probability that Z lies between -1.10 and -0.36. Chọn một câu trả lời  a. 0.4951 b. -0.2237 c. 0.2237 d. 0.2239 Không đúng Điểm: 0/1. Question 186 Điểm : 0/1 According to the 2003 National Survey on Drug Use and Health, 54.3% of males have never used marijuana. Based on this percentage, what is the expected number of males who have used marijuana for samples of size 100? Chọn một câu trả lời  a. 5 b. 24.8 c. 45.7 d. 50 Không đúng Điểm: 0/1. Question 187 Điểm : 0/1 It has been found that 40% of the employees who complete a sequence of executive seminars go on to become vice presidents. Assume that 10 graduates of the program are randomly selected, find the probability that from two to four become vice presidents. (Note: please give the answer as a real number accurate to 4 decimal places after the decimal point.) Đáp án : Không đúng Câu trả lời đúng: 0.5867 Điểm: 0/1. Lịch sử của các câu trả lời #Thực hiệnĐáp ánTimeRaw scoreĐiểm 1Điểm22:02:23 on 3/04/1100 2Close&Grade22:02:57 on 3/04/1100 Question 188 Điểm : 0/1 Sixty-five percent of men consider themselves knowledgeable football fans. If 13 men are randomly selected, find the probability that exactly five of them will consider themselves knowledgeable fans. Chọn một câu trả lời  a. 0.385 b. 0.215 c. 0.034 d. 0.65 Không đúng Điểm: 0/1. Question 189 Điểm : 0/1 The number of ounces of soda that a vending machine dispenses per cup is normally distributed with a mean of 12 ounces and a standard deviation of 4 ounces. Find the probability that more than 16 ounces is dispensed in a cup. Chọn một câu trả lời  a. 0.1521 b. 0.1687 c. 0.1587 d. 0.1621 Không đúng Điểm: 0/1. Question 190 Điểm : 0/1 Find the mean for the binomial distribution which has the stated values of n and p. Round answer to the nearest tenth. n = 33; p = 0.2 Chọn một câu trả lời  a. 7.3 b. 6.6 c. 6.9 d. 6.1 Không đúng Điểm: 0/1. Question 191 Điểm : 0/1 The weights of the fish in a certain lake are normally distributed with a mean of 15 lb and a standard deviation of 6. If 4 fish are randomly selected, what is the probability that the mean weight will be between 12.6 and 18.6 lb. Chọn một câu trả lời  a. 0.6730 b. 0.0968 c. 0.3270 d. 0.4032 Không đúng Điểm: 0/1. Question 192 Điểm : 0/1 The time (in years) until the first critical-part failure for a certain car is exponentially distributed with a mean of 3.4 years. Find the probability that the time until the first critical-part failure is 5 years or more. Chọn một câu trả lời  a. 0.506617 b. 0.493383 c. 0.770210 d. 0.229790 Không đúng Điểm: 0/1. Question 193 Điểm : 0/1 At a California college, 22% of students speak Spanish, 5% speak French, and 3% speak both languages. What is the probability that a student chosen at random from the college speaks Spanish but not French? Chọn một câu trả lời  a. 0.02 b. 0.17 c. 0.24 d. 0.19 Không đúng Điểm: 0/1. Question 194 Điểm : 0/1 Assume that the heights of women are normally distributed. A random sample of 20 women have a mean height of 62.5 inches and a standard deviation of 2.5 inches. Construct a 98% confidence interval for the population variance,$$\sigma^2.$$Chọn một câu trả lời  a. (1.3, 6.2) b. (1.8, 3.9) c. (3.3, 15.6) d. (3.5, 16.4) Không đúng Điểm: 0/1. Question 195 Điểm : 0/1 Construct the boxplot for the given data below: 3, 3, 5, 6, 4, 9, 8, 9, 6. Chọn một câu trả lời  a. b. c. d. Không đúng Điểm: 0/1. Question 196 Điểm : 0/1 A die is rolled 10 times and the number of times that two shows on the up face is counted. If this experiment is repeated many times, find the mean for the random variable X, the number of twos thrown out of ten tosses. Chọn một câu trả lời  a. 2.98 b. 8.33 c. 1.67 d. 3.33 Không đúng Điểm: 0/1. Question 197 Điểm : 0/1 Find the critical value or values of x2 based on the given information. H1: σ ≠ 9.3 n = 28 α = 0.05 Chọn một câu trả lời  a. -14.573, 14.573 b. -40.113, 40.113 c. 14.573, 43.194 d. 16.151, 40.113 Không đúng Điểm: 0/1. Question 198 Điểm : 0/1 A population of Australian Koala bears has a mean height of 20 inches and a standard deviation of 4 inches. You plan to choose a sample of 64 bears at random. What is the probability of a sample mean between 20 and 21. Chọn một câu trả lời  a. 0.9772 b. 0.4772 c. 0.5228 d. 0.5 Không đúng Điểm: 0/1. Question 199 Điểm : 0/1 Assume that a researcher randomly selects 14 newborn babies and counts the number of girls selected, X. The probabilities corresponding to the 14 possible values of x are summarized in the given table. Answer the question using the following table.  X(girls) 0 1 2 3 4 5 6 7 8 9 10 11 12 13 14 P(X) 0 0.001 0.006 0.022 0.061 0.122 0.183 0.209 0.183 0.122 0.061 0.022 0.006 0.001 0 Find the probability of selecting 9 or more girls. Chọn một câu trả lời  a. 0.061 b. 0.001 c. 0.212 d. 0.122 Không đúng Điểm: 0/1. Question 200 Điểm : 0/1 The random variable X represents the number of girls in a family of three children. Assuming that boys and girls are equally likely, find the mean and standard deviation for the random variable X. Chọn một câu trả lời  a. mean: 1.50; standard deviation: 0.87 b. mean: 1.50; standard deviation: 0.76 c. mean: 2.25; standard deviation: 0.76 d. mean: 2.25; standard deviation: 0.87 Không đúng Điểm: 0/1. Question 201 Điểm : 0/1 The amount of soda a dispensing machine pours into a 12 ounce can of soda follows a normal distribution with a mean of 12.27 ounces and a standard deviation of 0.18 ounce. The cans only hold 12.45 ounces of soda. Every can that has more than 12.45 ounces of soda poured into it causes a spill and the can needs to go through a special cleaning process before it can be sold. What is the probability a randomly selected can will need to go through this process? Chọn một câu trả lời  a. 0.6587 b. 0.8413 c. 0.1587 d. 0.3413 Không đúng Điểm: 0/1. Question 202 Điểm : 0/1 An electrical firm manufactures a certain type of light bulb that has a mean light of 1,800 hours and a standard deviation of 200 hours. Find the probability that a random sample of 100 bulbs will have an average life of more than 1,825 hours. Chọn một câu trả lời  a. 0.1056 b. 0.0384 c. 0.9616 d. 0.8944 Không đúng Điểm: 0/1. Question 203 Điểm : 0/1 A psychologist claims that more than 6.3 percent of the population suffers from professional problems due to extreme shyness. Use p, the true percentage of the population that suffers from extreme shyness. Express the null hypothesis H0 and the alternative hypothesis H1 in symbolic form. Chọn một câu trả lời  a. H0: p < 6.3%H1: p ≥ 6.3% b. H0: p = 6.3%H1: p < 6.3% c. H0: p = 6.3%H1: p > 6.3% d. H0: p > 6.3%H1: p ≤ 6.3% Không đúng Điểm: 0/1. Question 204 Điểm : 0/1 A major videocassette rental chain is considering opening a new store in an area that currently does not have any such stores. The chain will open if there is evidence that more than 25% households in the area are equipped with videocassette recorders (VCRs). It conducts a telephone poll of 300 randomly selected households in the area and finds that 96 have VCRs. The value of the test statistic in this problem is approximately equal to Chọn một câu trả lời  a. 1.94 b. 2.60 c. 2.80 d. 1.30 Không đúng Điểm: 0/1. Question 205 Điểm : 0/1 Which of the following is a discrete quantitative variable? Chọn một câu trả lời  a. The Dow Jones Industrial average b. The distance you drove yesterday. c. The volume of water released from a dam d. The number of employees of an insurance company Không đúng Điểm: 0/1. Question 206 Điểm : 0/1 Suppose that the probability that a particular brand of light bulb fails before 900 hours of use is 0.2. If you purchase 3 of these bulbs, what is the probability that at least one of them lasts 900 hours or more? Chọn một câu trả lời  a. 0.008 b. 0.992 c. 0.512 d. 0.6 Không đúng Điểm: 0/1. Question 207 Điểm : 0/1 Determine whether the given conditions justify testing a claim about a population mean μ. The sample size is n = 49, σ = 12.3, and the original population is not normally distributed. Chọn một câu trả lời  a. Yes b. No Không đúng Điểm: 0/1. Question 208 Điểm : 0/1 Which of the following is a continuous quantitative variable? Chọn một câu trả lời  a. The color of a student's eyes b. The number of gallons of milk sold at the local grocery store yesterday c. The number of employees of an insurance company d. The amount of milk produced by a cow in one 24-hour period Không đúng Điểm: 0/1. Question 209 Điểm : 0/1 Determine whether the hypothesis test involves a sampling distribution of means that is a normal distribution, Student t distribution, or neither. Claim: μ = 78. Sample data: n = 24,$$\overline{x} = 101,$$s = 15.3. The sample data appear to come from a population with a distribution that is very far from normal, and σ is unknown. Chọn một câu trả lời  a. Student t b. Neither c. Normal Không đúng Điểm: 0/1. Question 210 Điểm : 0/1 A supermarket manager has determined that the amount of time customers spend in the supermarket is approximately normally distributed with a mean of 45 minutes and a standard deviation of 6 minutes. Find the number of minutes, m, for which the probability that a customer spends less than m minutes in the supermarket is 0.10. Chọn một câu trả lời  a. 37.3 b. 27.3 c. 47.3 d. 17.3 Không đúng Điểm: 0/1. Question 211 Điểm : 0/1 If you flip a coin three times, the possible outcomes are HHH HHT HTH HTT THH THT TTH TTT. What is the probability of getting at least one head? Chọn một câu trả lời  a. 7/8 b. 5/6 c. 6/7 d. 1/2 Không đúng Điểm: 0/1. Question 212 Điểm : 0/1 The owner of a football team claims that the average attendance at games is over 60,000, and he is therefore justified in moving the team to a city with a larger stadium. Assume that a hypothesis test of the given claim will be conducted. Identify the type II error for the test. Chọn một câu trả lời  a. The error of failing to reject the claim that the mean attendance is at most 60,000, when it is actually greater than 60,000. b. The error of failing reject the claim that the mean attendance is more than 60,000, when it is actually less than 60,000. c. The error of rejecting the claim that the mean attendance is at most 60,000, when it really is at most 60,000. Không đúng Điểm: 0/1. Question 213 Điểm : 0/1 On a 10-question multiple choice test , each question has four possible answers, one of which is correct. For students who guess at all answers, find the mean for the random variable X, the number of correct answers. Chọn một câu trả lời  a. 2.5 b. 1.9 c. 3.3 d. 5 Không đúng Điểm: 0/1. Question 214 Điểm : 0/1 An economist is interested in studying the incomes of consumers in a particular region. The population standard deviation is known to be 1000. A random sample of 50 individuals resulted in an average income of 15000. What is the width of the 90% confidence interval? Chọn một câu trả lời  a. 232.60 b. 728.60 c. 364.30 d. 465.23 Không đúng Điểm: 0/1. Question 215 Điểm : 0/1 Assume that the data has a normal distribution and the number of observations is greater than fifty. Find the critical z value used to test a null hypothesis. α = 0.09 for a right-tailed test. Chọn một câu trả lời  a. +1.96 b. +1.34 c. ±1.34 d. ±1.96 Không đúng Điểm: 0/1. Question 216 Điểm : 0/1 Which of the following statements is false i) If X1, X2,…,Xn is a random sample of size n, the sample standard deviation S is not a statistic. ii) The probability distribution of a statistic is called a sampling distribution. iii) A statistic is any function of the observations in a random sample. iv) The sampling distribution of a statistic does not depend on the distribution of the population. Chọn một câu trả lời  a. i) only b. ii) and iii) c. i) and iv) d. i) and ii) Không đúng Điểm: 0/1. Question 217 Điểm : 0/1 An entomologist writes an article in a scientific journal which claims that fewer than 11 in ten thousand male fireflies are unable to produce light due to a genetic mutation. Use the parameter p, the true proportion of fireflies unable to produce light. Express the null hypothesis H0 and the alternative hypothesis H1 in symbolic form. Chọn một câu trả lời  a. H0: p = 0.0011H1: p > 0.0011 b. H0: p = 0.0011H1: p < 0.0011 c. H0: p > 0.0011H1: p ≤ 0.0011 d. H0: p < 0.0011H1: p ≥ 0.0011 Không đúng Điểm: 0/1. Question 218 Điểm : 0/1 According to a CNN poll taken in February of 2008, 67% of respondents disapproved of the overall job that President Bush was doing. Based on this poll, for samples of size 200, what is the mean number of American adults who disapprove of the overall job that President Bush is doing? Chọn một câu trả lời  a. 67 b. 6.65 c. 44.22 d. 134 Không đúng Điểm: 0/1. Question 219 Điểm : 0/1 A university dean is interested in determining the proportion of students who receive some sort of financial aid. Rather than examine the records for all students, the dean randomly selects 200 students and finds that 118 of them are receiving financial aid. Use a 95% confidence interval to estimate the true proportion of students on financial aid. Chọn một câu trả lời  a. 0.59 ±0 .005 b. 0.59 ±0.474 c. 0.59 ± 0.002 d. 0.59 ± 0.068 Không đúng Điểm: 0/1. Question 220 Điểm : 0/1 The peak shopping time at home improvement store is between 8-11:00 am on Saturday mornings. Management at the home improvement store randomly selected 150 customers last Saturday morning and decided to observe their shopping habits. They recorded the number of items that a sapmle of the customers purchased as well as the total time the customers spent in the store. Identify the types of variables recorded by the home improvement store. Chọn một câu trả lời  a. number of items - discrete; total time - continuous b. number of items - continuous; total time - continuous c. number of items - discrete; total time - discrete d. number of items - continuous; total time - discrete Không đúng Điểm: 0/1. Question 221 Điểm : 0/1 An airline reports that it has been experiencing a 15% rate of no-shows on advanced reservations. Among 150 advanced reservations, find the probability that there will be fewer than 20 no-shows. Chọn một câu trả lời  a. 0.7549 b. 0.3187 c. 0.251 d. 0.7967 Không đúng Điểm: 0/1. Question 222 Điểm : 0/1 The name of each contestant is written on a separate card, the cards are placed in a bag, and three names are picked from the bag. Identify which of these types of sampling is used: Stratified, systematic, cluster, random. Chọn một câu trả lời  a. Cluster b. Systematic c. Random d. Stratified Không đúng Điểm: 0/1. Question 223 Điểm : 0/1 A skeptical paranormal researcher claims that the proportion of Americans that have seen a UFO, p, is less than 1 in every one thousand. Assume that a hypothesis test of the given claim will be conducted. Identify the type II error for the test. Chọn một câu trả lời  a. The error of failing to reject the claim that the true proportion is at least 1 in one thousand when it is actually less than 1 in one thousand. b. The error of rejecting the claim that the true proportion is at least 1 in one thousand when it really is at least 1 in one thousand. c. The error of rejecting the claim that the true proportion is less than 1 in one thousand when it really is less than 1 in one thousand. Không đúng Điểm: 0/1. Question 224 Điểm : 0/1 A random sample of 40 students has a mean annual earnings of 3120 and a population standard deviation of 677. Construct the confidence interval for the population mean, μ. Use a 95% confidence level. Chọn một câu trả lời  a. (210, 110) b. (1987, 2346) c. (2910, 3330) d. (4812, 5342) Không đúng Điểm: 0/1. Question 225 Điểm : 0/1 An economist is interested in studying the incomes of consumers in a particular region. The normally population standard deviation is known to be 1000. What total sample size would the economist need to use for a 95% confidence interval if the width of the interval should not be more than 100? Let$$z_{0.025}=1.96; z_{0.05}=1.65$$. Chọn một câu trả lời  a. n = 1537 b. n = 385 c. n = 40 d. n = 20 Không đúng Điểm: 0/1. Question 226 Điểm : 0/1 The time (in years) until the first critical-part failure for a certain car is exponentially distributed with a mean of 3.4 years. Find the probability that the time until the first critical-part failure is less than 1 year. Chọn một câu trả lời  a. 0.254811 b. 0.966627 c. 0.745189 d. 0.033373 Không đúng Điểm: 0/1. Question 227 Điểm : 0/1 A study of the amount of time it take a mechanic to rebuild the transmission for a 1992 Chevrolet Cavalier shows that the mean is 8.4 hours and the standard deviation is 1.8 hours. If 40 mechanics are randomly selected, find the probability that their mean rebuild time exceeds 8.7 hours. Chọn một câu trả lời  a. 0.1946 b. 0.1285 c. 0.1469 d. 0.1346 Không đúng Điểm: 0/1. Question 228 Điểm : 0/1 Suppose x is a uniform random variable over [10,90]. Find the probability that a randomly selected observation exceeds 26. Chọn một câu trả lời  a. 0.2 b. 0.1 c. 0.8 d. 0.9 Không đúng Điểm: 0/1. Question 229 Điểm : 0/1 A university dean is interested in determining the proportion of students who receive some sort of financial aid. Rather than examine the records for all students, the dean randomly selects 200 students and finds that 118 of them are receiving financial aid. Use a 90\% confidence interval to estimate the true proportion of students who receive financial aid. Let$$z_{0.1}=1.28;z_{0.05}=1.65$$. Chọn một câu trả lời  a. (0.143; 0.641) b. (0.433; 0.567) c. (0.533; 0.647) d. (0.563; 0.723) Không đúng Điểm: 0/1. Question 230 Điểm : 0/1 To determine the mean of a binomial distribution, it is necessary to know the number of successes involved in the problem. Chọn một câu trả lời  a. False b. True Không đúng Điểm: 0/1. Question 231 Điểm : 0/1 Which of the following is always true for a normal distribution? Chọn một câu trả lời  a. P(x ≤ 8) = P(x ≤ 8.5) b. P(2< x ≤ 8) = P(2 ≤ x < 8) c. P(x > 8) = P(x ≥ 9) d. P(x < 5) ≠ P(x ≤ 5) Không đúng Điểm: 0/1. Question 232 Điểm : 0/1 Find the normal-curve area between z = -1.48 and z = 0. Chọn một câu trả lời  a. 0.8712 b. 0.1288 c. 0.5694 d. 0.4306 Không đúng Điểm: 0/1. Question 233 Điểm : 0/1 Brandon and Samantha each carry a bag containing a banana, a chocolate bar, and a licorice stick. Simultaneously, they take out a single food item and consume it. The possible pairs of food items that Brandon and Samantha consumed are as follows. chocolate bar - chocolate bar licorice stick - chocolate bar banana - banana chocolate bar - licorice stick licorice stick - licorice stick chocolate bar - banana banana - licorice stick licorice stick - banana banana - chocolate bar Find the probability that at least one chocolate bar was eaten. Chọn một câu trả lời  a. 5/9 b. 4/9 c. 1/3 d. 1/2 Không đúng Điểm: 0/1. Question 234 Điểm : 0/1 A study of 1000 randomly selected flights of a major airline showed that 782 of the flights arrived on time. What is the probability of a flight arriving on time? Chọn một câu trả lời  a. 391/500 b. 500/109 c. 109/500 d. 102/207 Không đúng Điểm: 0/1. Question 235 Điểm : 0/1 Assume that the weights of quarters are normally distributed with a mean of 5.67 g and a standard deviation 0.070 g. A vending machine will only accept coins weighing between 5.48 g and 5.82 g. What percentage of legal quarters will be rejected? Chọn một câu trả lời  a. 2.48% b. 1.62% c. 1.96% d. 3.92% Không đúng Điểm: 0/1. Question 236 Điểm : 0/1 In a recent survey, 80% of the community favored building a police substation in their neighborhood. If 15 citizens are chosen, what is the mean number favoring the substation? Chọn một câu trả lời  a. 15 b. 10 c. 12 d. 8 Không đúng Điểm: 0/1. Question 237 Điểm : 0/1 The tread life of a particular brand of tire is a random variable best described by a normal distribution with a mean of 60,000 miles and a standard deviation of 1900 miles. What is the probability a certain tire of this brand will last between 56,010 miles and 56,580 miles? Chọn một câu trả lời  a. 0.4920 b. 0.0180 c. 0.9813 d. 0.4649 Không đúng Điểm: 0/1. Question 238 Điểm : 0/1 According to a 2007 report published by the National Center on Addiction and Substance Abuse at Columbia University, 59% of teens have family dinners five or more times a week, 13% of teens have used marijuana and the proportion of teens who have family dinners 5 or more times a week or use marijuana is 0.64. What is the probability that a teen has family dinners five or more times a week and uses marijuana? Hint. Use the addition rules. Chọn một câu trả lời  a. 0.077 b. 0.08 c. 0.64 d. 0.18 Không đúng Điểm: 0/1. Question 239 Điểm : 0/1 A percentage distribution is given below for the size of families in one U.S. city. Size Percentage 2 45.1 3 22.2 4 19.7 5 8.0 6 3.1 7+ 1.9 A family is selected at random. Find the probability that the size of the family is less than 6. Round your result to three decimal places. Chọn một câu trả lời  a. 0.050 b. 0.019 c. 0.950 d. 0.031 Không đúng Điểm: 0/1. Question 240 Điểm : 0/1 The principal of a middle school claims that test scores of the seventh-graders at her school vary less than the test scores of seventh-graders at a neighboring school, which have variation described by σ = 14.7. Express the null hypothesis H0 and the alternative hypothesis H1 in symbolic form. Chọn một câu trả lời  a. H0: σ > 14.7H1: σ ≤ 14.7 b. H0: σ = 14.7H1: σ < 14.7 c. H0: σ < 14.7H1: σ > 14.7 d. H0: σ = 14.7H1: σ > 14.7 Không đúng Điểm: 0/1. Question 241 Điểm : 0/1 To calculate the probability of obtaining three aces in eight draws of a card with replacement from an ordinary deck, we would use the Chọn một câu trả lời  a. discrete uniform distribution. b. binomial distribution. c. hypergeometric distribution. d. Poisson distribution. Không đúng Điểm: 0/1. Question 242 Điểm : 0/1 The outcome of an experiment is the number of resulting heads when a nickel and a dime are flipped simultaneously. What is the sample space for this experiment? Chọn một câu trả lời  a. {HH, HT, TH, TT} b. {nickel, dime} c. {HH, HT, TT} d. {0, 1, 2} Không đúng Điểm: 0/1. Question 243 Điểm : 0/1 If we are using the normal approximation to determine the probability of at most 28 successes in a binomial distribution P(x ≤ 28) the normal distribution probability that is used to make the estimate is Chọn một câu trả lời  a. P(x ≤ 28.5). b. P(x < 28). c. P(x ≤ 27.5). d. P(x ≤ 28). Không đúng Điểm: 0/1. Question 244 Điểm : 0/1 The use of the Poisson distribution requires a value n which indicates a definite number of independent trials. Chọn một câu trả lời  a. False b. True Không đúng Điểm: 0/1. Question 245 Điểm : 0/1 The process of using sample statistics to draw conclusions about true population parameters is called Chọn một câu trả lời  a. descriptive statistics. b. the scientific method. c. sampling. d. statistical inference. Không đúng Điểm: 0/1. Question 246 Điểm : 0/1 In 2006, the percent of the voting-age population that was registered to vote for the 50 states and the District of Columbia had a mean of 65% with a standard deviation of 7.1. Assuming that the distribution is normal, what percentage of states had between 50 and 70 percent of it's voting-age population who were registered to vote? Chọn một câu trả lời  a. 0.74 b. 0.68 c. 0.65 d. 0.95 Không đúng Điểm: 0/1. Question 247 Điểm : 0/1 A stock analyst compares the relationship between stock prices and earnings per share to help him select a stock for investment. What type of the description is? Chọn một câu trả lời  a. Experiment b. Retrospective study c. Observation study Không đúng Điểm: 0/1. Question 248 Điểm : 0/1 According to a college survey, 22% of all students work full time. Find the mean for the random variable X, the number of students who work full time in samples of size 16. Chọn một câu trả lời  a. 0.22 b. 2.75 c. 4.00 d. 3.52 Không đúng Điểm: 0/1. Question 249 Điểm : 0/1 The following table contains the probability distribution for X = the number of traffic accidents reported in a day in Hanoi.  X 0 1 2 3 4 5 P(X) 0.1 0.2 0.45 0.15 0.05 0.05 The probability of more than 2 accidents is Chọn một câu trả lời  a. 0.45 b. 0.75 c. 0.55 d. 0.25 Không đúng Điểm: 0/1. Question 250 Điểm : 0/1 A Type II error is committed when Chọn một câu trả lời  a. we reject a null hypothesis that is true. b. we reject a null hypothesis that is false. c. we don't reject a null hypothesis that is false. d. we don't reject a null hypothesis that is true. Không đúng Điểm: 0/1. Question 251 Điểm : 0/1 Use the given information to find the P-value. The test statistic in a right-tailed test is z = 0.52. Chọn một câu trả lời  a. 0.1915 b. 0.3015 c. 0.1950 d. 0.5530 Không đúng Điểm: 0/1. Question 252 Điểm : 0/1 A company had 80 employees whose salaries are summarized in the frequency distribution below. Find the mean salary. Chọn một câu trả lời  a. b. c. d. Không đúng Điểm: 0/1. Question 253 Điểm : 0/1 According to the Center for Disease Control, in 2004, 65.7% of all adults between the ages of 18 and 44 were considered current drinkers. Based on this estimate, if two randomly selected adults between the ages of 18 and 44 are selected, what is the probability that at least one is a current drinker? Chọn một câu trả lời  a. 0.43 b. 1 c. 0.57 d. 0.88 Không đúng Điểm: 0/1. Question 254 Điểm : 0/1 An article a Florida newspaper reported on the topics that teenagers most want to discuss with their parents. The findings, the results of a poll, showed that 46% would like more discussion about the family's financial situation, 37% would like to talk about school, and 30% would like to talk about religion. These and other percentages were based on a national sampling of 549 teenagers. Estimate the proportion of all teenagers who want more family discussions about school. Use a 99% confidence level. Chọn một câu trả lời  a. 0.63 ± .053 b. 0.63 ± .002 c. 0.37 ± .053 d. 0.37 ± .002 Không đúng Điểm: 0/1. Question 255 Điểm : 0/1 Which of the following is not true of statistics? Chọn một câu trả lời  a. Statistics involves collecting and summarizing data. b. Statistics is used to draw conclusions using data. c. Statistics is used to answer questions with 100% certainty. d. Statistics can be used to organize and analyze information. Không đúng Điểm: 0/1. Question 256 Điểm : 0/1 A group of 40 bowlers showed that their average score was 192 with a population standard deviation of 8. Find the 95% confidence interval of the mean score of all bowlers. Chọn một câu trả lời  a. (189.5, 194.5) b. (187.3, 196.1) c. (186.5, 197.5) d. (188.5, 195.6) Không đúng Điểm: 0/1. Question 257 Điểm : 0/1 The number of ounces of soda that a vending machine dispenses per cup is normally distributed with a mean of 12 ounces and a standard deviation of 4 ounces. Find the probability that between 15 and 18 ounces are dispensed in a cup. Chọn một câu trả lời  a. 0.3481 b. 0.4365 c. 0.1598 d. 0.9834 Không đúng Điểm: 0/1. Question 258 Điểm : 0/1 Let X be a uniform random variable over the interval [0, 8] . What is the probability that the random variable X has a value greater than 3? Chọn một câu trả lời  a. 0.750 b. 0.575 c. 0.625 d. 0.500 Không đúng Điểm: 0/1. Question 259 Điểm : 0/1 A confidence interval was used to estimate the proportion of statistics students that are female. A random sample of 72 statistics students generated the following 90% confidence interval: (0.438, 0.642). Using the information above, what total size sample would be necessary if we wanted to estimate the true proportion to within 0.08 using 95% confidence? Chọn một câu trả lời  a. 150 b. 420 c. 105 d. 597 Không đúng Điểm: 0/1. Question 260 Điểm : 0/1 The area to the right of z = 1.0 is equal to Chọn một câu trả lời  a. 0.1587. b. 0.8413. c. 0.3413. d. 0.6816. Không đúng Điểm: 0/1. Question 261 Điểm : 0/1 Use the given information to find the P-value. The test statistic in a left-tailed test is z = -2.05. Chọn một câu trả lời  a. 0.4798 b. 0.0202 c. 0.0453 d. 0.5000 Không đúng Điểm: 0/1. Question 262 Điểm : 0/1 Suppose that11% of people are left handed. If 6 people are selected at random, what is the probability that exactly 2 of them are left handed? Chọn một câu trả lời  a. 0.0121 b. 0.0076 c. 0.1139 d. 0.2278 Không đúng Điểm: 0/1. Question 263 Điểm : 0/1 Suppose that the random variable X has an exponential distribution with λ = 1.5. Find the mean and standard deviation of X. Chọn một câu trả lời  a. Mean = 0.67; Standard deviation = 1 b. Mean = 0; Standard deviation = 1 c. Mean = 0; Standard deviation = 1.5 d. Mean = 0.67; Standard deviation = 0.44 Không đúng Điểm: 0/1. Question 264 Điểm : 0/1 A survey of senior citizens at a doctor's office shows that 52% take blood pressure-lowering medication, 43% take cholesterol-lowering medication, and 5% take both medications. What is the probability that a senior citizen takes either blood pressure-lowering or cholesterol-lowering medication? Chọn một câu trả lời  a. 0.85 b. 1 c. 0.14 d. 0.90 Không đúng Điểm: 0/1. Question 265 Điểm : 0/1 The diameters of bolts produced by a certain machine are normally distributed with a mean of 0.30 inches and a standard deviation of 0.01 inches. What percentage of bolts will have a diameter greater than 0.32 inches? Chọn một câu trả lời  a. 97.72% b. 47.72% c. 2.28% d. 37.45% Không đúng Điểm: 0/1. Question 266 Điểm : 0/1 Assume that the heights of men are normally distributed. A random sample of 16 men have a mean height of 67.5 inches and a standard deviation of 2.2 inches. Construct a 99% confidence interval for the population standard deviation. Let$$\chi_{0.005,15}^2=32.8;\chi_{0.995,15}^2=4.6$$. Chọn một câu trả lời  a. (1.5, 4.0) b. (1.0, 2.7) c. (1.5, 4.1) d. (1.5, 3.7) Không đúng Điểm: 0/1. Question 267 Điểm : 0/1 If Z is a standard normal variable, find the the probability that Z is less than 1.13. Chọn một câu trả lời  a. 0.8907 b. 0.8708 c. 0.1292 d. 0.8485 Không đúng Điểm: 0/1. Question 268 Điểm : 0/1 For women aged 18-24, systolic blood pressures ( in mm Hg) are normally distributed with a mean of 114.8 and a standard deviation of 13.1. If 23 women aged 18-24 are randomly selected, find the probability that their mean systolic blood pressures is between 119 and 122. Chọn một câu trả lời  a. 0.9341 b. 0.3343 c. 0.0833 d. 0.0577 Không đúng Điểm: 0/1. Question 269 Điểm : 0/1 According to a survey of American households, the probability that the residents own 2 cars if annual household income is over 25,000 is 80%. Of the households surveyed, 60% had incomes over 25,000 and 70% had 2 cars. The probability that the residents of a household own 2 cars and have an income over 25,000 a year is: Chọn một câu trả lời  a. 0.18 b. 0.48 c. 0.12 d. 0.22 Không đúng Điểm: 0/1. Question 270 Điểm : 0/1 A nurse measured the blood pressure of each person who visited her clinic. Following is a relative-frequence histogram for the systolic blood pressure readings for those people aged between 25 and 40. The blood pressure reading were given to the nearest whole number. Approximately what percentage of the people aged 25-40 had a systolic blood pressure reading between 110 and 119 inclusive? Chọn một câu trả lời  a. 0.35% b. 3.5% c. 35% d. 30% Không đúng Điểm: 0/1. Question 271 Điểm : 0/1 Assume that a procedure yields a binomial distribution with a trial repeated n times. Use the binomial probability formula to find the probability of x successes given the probability p of success on a single trial. n = 64, x = 3, p = 0.04 Chọn một câu trả lời  a. 0.091 b. 0.139 c. 0.221 d. 0.375 Không đúng Điểm: 0/1. Question 272 Điểm : 0/1 Private colleges and universities rely on money contributed by individuals and corporations for their operating expenses. Much of this money is put into a fund called an endowment, and the college spends only the interest earned by the fund. A recent survey of 8 private colleges in Vietnam revealed the following endowments (in millions of dollars) 60.2, 47.0, 235.1, 490.0, 122.6, 177.5, 95.4, and 220.0. What value will be used as the point estimate for the mean endowment of all private colleges in Vietnam? Chọn một câu trả lời  a. 180.975 b. 1447.8 c. 143.042 d. 8 Không đúng Điểm: 0/1. Question 273 Điểm : 0/1 The number of 113 calls in Hanoi, has a Poisson distribution with a mean of 10 calls a day. The probability of seven 113 calls in a day is Chọn một câu trả lời  a. 0.62 b. 0.09 c. 0.24 d. 0.22 Không đúng Điểm: 0/1. Question 274 Điểm : 0/1 Find the normal-curve area between z = -2 and z = -1. Chọn một câu trả lời  a. 0.2388 b. 0.7612 c. 0.1359 d. 0.8641 Không đúng Điểm: 0/1. Question 275 Điểm : 0/1 Assume that z scores are normally distributed with a mean of 0 and a standard deviation of 1. If P(0.2 < Z < a) = 0.2314, find a. Chọn một câu trả lời  a. 0.8805 b. 1.4906 c. 0.3542 d. -0.1821 Không đúng Điểm: 0/1. Question 276 Điểm : 0/1 If a random variable has the normal distribution with μ = 30 and σ = 5, find the probability that it will take on the value between 24 and 28. Chọn một câu trả lời  a. 0.6295 b. 0.3295 c. 0.2295 d. 0.4295 Không đúng Điểm: 0/1. Question 277 Điểm : 0/1 A 99% confidence interval estimate can be interpreted to mean that Chọn một câu trả lời  a. Both of the above. b. if all possible samples are taken and confidence interval estimates are developed, 99% of them would include the true population mean somewhere within their interval. c. None of the above. d. we have 99% confidence that we have selected a sample whose interval does include the population mean. Không đúng Điểm: 0/1. Question 278 Điểm : 0/1 In 2006, the General Social Survey asked 4,491 respondents how often they attended religious services. The responses were as follows:  Frequency Number of respondents Never 1020 Less than once a year 302 Once a year 571 Several times a year 502 Once a month 308 Two-three times a month 380 Nearly every week 240 Every week 839 More than once a week 329 What is the probability that a randomly selected respondent attended religious services more than once a year? Chọn một câu trả lời  a. 0.58 b. 0.13 c. 0.42 d. 0.71 Không đúng Điểm: 0/1. Question 279 Điểm : 0/1 Find z if the normal curve area between 0 and z is 0.4756. Chọn một câu trả lời  a. -1.9703 b. 2.9703 c. -2.9703 d. 1.9703 Không đúng Điểm: 0/1. Question 280 Điểm : 0/1 The paired data below consist of the test scores of 6 randomly selected students and the number of hours they studied for the test.  Hours 5 10 4 6 10 9 Score 4 8 3 6 9 8$$
Find the value of the linear correlation coefficient $$r$$.
Chọn một câu trả lời
 a. -0.678 b. 0.678 c. -0.224 d. 0.973
Không đúng
Điểm: 0/1.
Question 281
Điểm : 0/1
A catalog company that receives the majority of its orders by telephone conducted a study to determine how long customers were willing to wait on hold before ordering a product. The length of time was found to be a random variable best approximated by an exponential distribution with a mean equal to 3 minutes. Find the waiting time at which only 10% of the customers will continue to hold.
Chọn một câu trả lời
 a. 2.3 minutes b. 13.8 minutes c. 6.9 minutes d. 3.3 minutes
Không đúng
Điểm: 0/1.
Question 282
Điểm : 0/1

Construct a 95% confidence interval for the population mean, μ. Assume the population has a normal distribution. A sample of 25 randomly selected students has a mean test score of 81.5 with a standard deviation of 10.2.

Chọn một câu trả lời
 a. (66.35, 69.89) b. (87.12, 98.32) c. (77.29, 85.71) d. (56.12, 78.34)
Không đúng
Điểm: 0/1.
Question 283
Điểm : 0/1

Patients arriving at an outpatient clinic follow an exponential distribution at a rate of 15 patients per hour. What is the probability that a randomly chosen arrival to be less than 15 minutes?

Chọn một câu trả lời
 a. 0.0165 b. 0.2465 c. 0.5765 d. 0.9765
Không đúng
Điểm: 0/1.
Question 284
Điểm : 0/1

A student randomly selects 10 CDs at a store. The mean is $8.75 with a standard deviation of$1.50. Construct a 95% confidence interval for the population standard deviation, $$\sigma.$$ Assume the data are normally distributed.

Chọn một câu trả lời
 a. ($1.03,$2.74) b. ($0.43,$1.32) c. ($1.76,$3.10) d. ($1.43,$2.70)
Không đúng
Điểm: 0/1.
Question 285
Điểm : 0/1
If $$n = 10$$ and $$p = 0.70$$, then the standard deviation of the binomial distribution is
Chọn một câu trả lời
 a. 14.29 b. 7.00 c. 0.07 d. 1.45
Không đúng
Điểm: 0/1.
Question 286
Điểm : 0/1
A telemarketer found that there was a 1% chance of a sale from his phone solicitations. Find the probability of getting 5 or more sales for 1000 telephone calls.
Chọn một câu trả lời
 a. 0.8810 b. 0.9599 c. 0.0871 d. 0.0401
Không đúng
Điểm: 0/1.
Question 287
Điểm : 0/1
Which of the following cannot be a probability?
Chọn một câu trả lời
 a. 1 b. 86% c. 4/3 d. 0.4
Không đúng
Điểm: 0/1.
Question 288
Điểm : 0/1
Find the variance of the given data. Round your answer to one more decimals than the original data.
Chọn một câu trả lời
 a. 3.96 b. 3.17 c. 10.26 d. 3.86
Không đúng
Điểm: 0/1.
Question 289
Điểm : 0/1
In 2005, the property crime rates (per 100,000 residents) for the 50 states and the District of Columbia had a mean of 3377.2 and a standard deviation of 847.4. Assuming the distribution of property crime rates is normal, what percentage of the states had property crime rates between 2360 and 4055?
Chọn một câu trả lời
 a. 0.67 b. 0.10 c. 0.95 d. 0.68
Không đúng
Điểm: 0/1.
Question 290
Điểm : 0/1

According to the U.S. census, in 2005 21% of homicide vic