1) Sampling distributions describe the distribution of
A) parameters.
B) statistics.
C) both parameters and statistics.
D) neither parameters nor statistics.
1) B
2) The Central Limit Theorem is important in statistics because
A) for any sized sample, it says the sampling distribution of the sample mean is approximately normal.
B) for a large n, it says the population is approximately normal.
C) for any population,
2) D
3) For air travelers, one of the biggest complaints involves the waiting time between when the airplane taxis away from the terminal until the flight takes off. This waiting time is known to have a skewed-right distribution with a mean of 10 minutes and a
3) A
4) Which of the following statements about the sampling distribution of the sample mean is INCORRECT?
A) The sampling distribution of the sample mean is generated by repeatedly taking samples of size n and computing the sample means.
B) The sampling distr
4) C
5) Suppose the ages of students in Statistics 101 follow a skewed-right distribution with a mean of 23 years and a standard deviation of 3 years. If we randomly sampled 100 students, which of the following statements about the sampling distribution of the
5) A
6) A sample that does not provide a good representation of the population from which it was collected is referred to as a(n) __________ sample.
6) biased
7) Suppose a sample of n = 50 items is drawn from a population of manufactured products and the weight, X, of each item is recorded. Prior experience has shown that the weight has a probability distribution with ? = 6 ounces and ? = 2.5 ounces. Which of t
7) A
8) Major league baseball salaries averaged $1.5 million with a standard deviation of $0.8 million in 1994. Suppose a sample of 100 major league players was taken. Find the approximate probability that the average salary of the 100 players exceeded $1 mill
8) A
9) 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 centimeters. A random sample of 12 computer chips is taken. What is the probability that the samp
9) 0.2710
10) The owner of a fish market has an assistant who has determined that the weights of catfish are normally distributed, with mean of 3.2 pounds and a standard deviation of 0.8 pounds. If a sample of 16 fish is taken, what would the standard error of the
10) A
11) The owner of a fish market has an assistant who has determined that the weights of catfish are normally distributed, with mean of 3.2 pounds and a standard deviation of 0.8 pounds. If a sample of 64 fish yields a mean of 3.4 pounds, what is probabilit
11) D
12) The standard error of the mean for a sample of 100 is 30. In order to cut the standard error of the mean to 15, we would
A) increase the sample size to 400.B) decrease the sample size to 50.
C) increase the sample size to 200.
D) decrease the sample t
12) A
13) Which of the following is true regarding the sampling distribution of the mean for a large sample size?
A) It has the same shape, mean, and standard deviation as the population.
B) It has a normal distribution with the same mean as the population but
13) B
14) True or False: Suppose ? = 50 and ?2 = 100 for a population. In a sample where n = 100 is randomly taken, 95% of all possible sample means will fall between 48.04 and 51.96.
A) True
B) False
14) A
15) True or False: Suppose ? = 50 and ?2 = 100 for a population. In a sample where n = 100 is randomly taken, 90% of all possible sample means will fall between 49 and 51.
A) True
B) False
15) B
16) The width of a confidence interval estimate for a proportion mean will be
A) narrower for 90% confidence than for 95% confidence.
B) wider for a sample size of 100 than for a sample size of 50.
C) narrower when the sample proportion is 0.50 than when
16) A
17) 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
A) 2.7874
B) 2.7970
C) 2.4851
D) 2.4922
17) B
18) The t distribution
A) has more area in the tails than does the standard normal distribution.
B) assumes the population is normally distributed.
C) approaches the normal distribution as the sample size increases.
D) all of the above
18) D
19) 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 ($2,181,260, $5,836,180). Which of the following interpretations i
19) B
20) When determining the sample size necessary for estimating the true population mean, which factor is NOT considered when sampling with replacement?
A) the population size
B) the level of confidence desired in the estimate
C) the population standard dev
20) A
21) Suppose a 95% confidence interval for ? turns out to be (1,000, 2,100). To make more useful inferences from the data, it is desired to reduce the width of the confidence interval. Which of the following will result in a reduced interval width?
A) incr
21) D
22) In the construction of confidence intervals, if all other quantities are unchanged, an increase in the sample size will lead to a __________ interval.
A) narrower
B) less significant
C) biased
D) wider
22) A
23) A major department store chain is interested in estimating the average amount its credit card customers spent on their first visit to the chain's new store in the mall. Fifteen credit card accounts were randomly sampled and analyzed with the following
23) A
24) 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
24) C
25) A university system enrolling hundreds of thousands of students is considering a change in the way students pay for their education. Presently the students pay $55 per credit hour. The university system administrators are contemplating charging each s
25) n = 2033
26) An economist is interested in studying the incomes of consumers in a particular region. The population standard deviation is known to be $1,000. A random sample of 50 individuals resulted in an average income of $15,000. What is the width of the 90% c
26) C
27) The head librarian at the Library of Congress has asked her assistant for an interval estimate of the mean number of books checked out each day. The assistant provides the following interval estimate: from 740 to 920 books per day. What is an efficien
27) D
28) The head librarian at the Library of Congress has asked her assistant for an interval estimate of the mean number of books checked out each day. The assistant provides the following interval estimate: from 740 to 920 books per day. If the head librari
28) D
29) True or False: A race car driver tested his car for time from 0 to 60 mph, and in 20 tests obtained an average of 4.85 seconds with a standard deviation of 1.47 seconds. A 95% confidence interval for the 0 to 60 time is 4.52 seconds to 5.18 seconds.
A
29) B
30) True or False: Given a sample mean of 2.1 and a population standard deviation of 0.7, a 90% confidence interval will have a width of 2.36.
A) True B) False
30) B
31) Which of the following would be an appropriate null hypothesis?
A) The mean of a population is greater than 55.
B) The mean of a population is equal to 55.
C) The mean of a sample is equal to 55.
D) Only A and C are true.
31) B
32) Which of the following would be an appropriate alternative hypothesis?
A) The mean of a sample is equal to 55.
B) The mean of a population is equal to 55.
C) The mean of a population is greater than 55.
D) The mean of a sample is greater than 55.
32) C
33) A Type I error is committed when
A) we don't reject a null hypothesis that is true.
B) we reject a null hypothesis that is true.
C) we don't reject a null hypothesis that is false.
D) we reject a null hypothesis that is false.
33) B
34) The power of a test is measured by its capability of
A) rejecting a null hypothesis that is true.
B) not rejecting a null hypothesis that is false.
C) not rejecting a null hypothesis that is true.
D) rejecting a null hypothesis that is false.
34) D
35) True or False: For a given level of significance, if the sample size is increased, the probability of committing a Type II error will increase.
A) True B) False
35) B
36) If an economist wishes to determine whether there is evidence that average family income in a community exceeds $25,000
A) a one-tailed test should be utilized.
B) either a one-tailed or two-tailed test could be used with equivalent results.
C) a two-
36) A
37) If an economist wishes to determine whether there is evidence that average family income in a community equals $25,000
A) a two-tailed test should be utilized.
B) a one-tailed test should be utilized.
C) either a one-tailed or two-tailed test could be
37) A
38) If the Type I error (?) for a given test is to be decreased, then for a fixed sample size n
A) the Type II error (?) will increase.B) the power of the test will increase.
C) a one-tailed test must be utilized.
D) the Type II error (?) will also decrea
38) A
39) The power of a statistical test is
A) the probability of not rejecting H0 when it is false.
B) the probability of rejecting H0 when it is false.
C) the probability of not rejecting H0 when it is true.
D) the probability of rejecting H0 when it is true
39) B
40) How many Kleenex should the Kimberly Clark Corporation package of tissues contain? Researchers determined that 60 tissues is the average number of tissues used during a cold. Suppose a random sample of 100 Kleenex users yielded the following data on t
40 C
41) How many Kleenex should the Kimberly Clark Corporation package of tissues contain? Researchers determined that 60 tissues is the average number of tissues used during a cold. Suppose a random sample of 100 Kleenex users yielded the following data on t
41) A
42) How many Kleenex should the Kimberly Clark Corporation package of tissues contain? Researchers determined that 60 tissues is the average number of tissues used during a cold. Suppose a random sample of 100 Kleenex users yielded the following data on t
42) D
43) How many Kleenex should the Kimberly Clark Corporation package of tissues contain? Researchers determined that 60 tissues is the average number of tissues used during a cold. Suppose a random sample of 100 Kleenex users yielded the following data on t
43) C & B too
44) If, as a result of a hypothesis test, we reject the null hypothesis when it is false, then we have committed
A) a Type II error.
B) an acceptance error.
C) no error.
D) a Type I error.
44) C