- A population of size 320 has a proportion equal to .60 for the characteristic of interest. What are the mean and the standard deviation, respectively, of the sample proportion for samples of size 12?
| a. .60 and .02 |
| b. .60 and .14 |
| c. 320 and .02 |
| d. 192 and 45 |
2. A finite population correction factor is needed in computing the standard deviation of the sampling distribution of sample means
| a. whenever the sample size is more than 5% of the population size. |
| b. whenever the sample size is less than 5% of the population size. |
| c. irrespective of the size of the sample. |
| d. whenever the population is infinite. |
3. A simple random sample of size n from an infinite population of size N is to be selected. Each possible sample should have
| a. a probability of 1/n of being selected |
| b. the same probability of being selected |
| c. a probability of 1/N of being selected |
| d. a probability of N/n of being selected |
4. The sample statistic, such as x̄, s, or p̄, that provides the point estimate of the population parameter is known as
| a. a parameter. |
| b. a point estimator. |
| c. a population parameter. |
| d. a population statistic. |
5. All of the following are true about the standard error of the mean except
| a. its value is influenced by the standard deviation of the population. |
| b. it measures the variability in sample means. |
| c. it decreases as the sample size increases. |
| d. it is larger than the standard deviation of the population. |
6. Which of the following best describes the form of the sampling distribution of the sample proportion?
| a. It is approximately normal as long as np ≥ 5 and n(1 – p) ≥ 5. |
| b. When standardized, it is the t distribution. |
| c. When standardized, it is exactly the standard normal distribution. |
| d. It is approximately normal as long as n ≥ 30. |
7. The sampling distribution of the sample means
| a. is used as a point estimator of the population mean μ. |
| b. shows the distribution of all possible values of μ. |
| c. is an unbiased estimator. |
| d. is the probability distribution showing all possible values of the sample mean. |
8. A sample of 51 observations will be taken from an infinite population. The population proportion equals 0.85. The probability that the sample proportion will be between 0.9115 and 0.946 is
| a. 0.8633 |
| b. 0.0345 |
| c. 0.6900 |
| d. 0.0819 |
9. A sample of 66 observations will be taken from an infinite population. The population proportion equals 0.12. The probability that the sample proportion will be less than 0.1768 is
| a. 0.4222 |
| b. 0.0778 |
| c. 0.9222 |
| d. 0.0568 |
10. Random samples of size 81 are taken from an infinite population whose mean and standard deviation are 200 and 18, respectively. The distribution of the population is unknown. The mean and the standard error of the mean are
| a. 200 and 2 |
| b. 200 and 18 |
| c. 81 and 18 |
| d. 9 and 2 |
11. The following data was collected from a simple random sample of a population.
| 13 | 15 | 14 | 16 | 12 |
If the population consisted of 10 elements, how many different random samples of size 6 could be drawn from the population?
| a. 362880 |
| b. 60 |
| c. 210 |
| d. 3024 |
12. sampling distribution of x̄ is the
| a. mean of the sample. |
| b. probability distribution of the sample proportion. |
| c. probability distribution of the sample mean. |
| d. mean of the population |
13. The standard deviation of a point estimator is called the
| a. point estimator. |
| b. variance of estimation. |
| c. standard deviation. |
| d. standard error. |
14. A sample of 400 observations will be taken from an infinite population. The population proportion equals 0.8. The probability that the sample proportion will be greater than 0.83 is
| a. 0.9332 |
| b. 0.4332 |
| c. 0.5668 |
| d. 0.0668 |
15. A population consists of 500 elements. We want to draw a simple random sample of 50 elements from this population. On the first selection, the probability of an element being selected is
| a. 0.010 |
| b. 0.100 |
| c. 0.002 |
| d. 0.001 |
16. A population has a mean of 84 and a standard deviation of 12. A sample of 36 observations will be taken. The probability that the sample mean will be between 80.54 and 88.9 is
| a. 0.7200 |
| b. 8.3600 |
| c. 0.0347 |
| d. 0.9511 |
17. Random samples of size 17 are taken from a population that has 200 elements, a mean of 36, and a standard deviation of 8. The mean and the standard deviation of the sampling distribution of the sample means are
| a. 36 and 1.86. |
| b. 36 and 8. |
| c. 8.7 and 1.94. |
| d. 36 and 1.94 |
18. A population has a mean of 80 and a standard deviation of 7. A sample of 49 observations will be taken. The probability that the sample mean will be larger than 82 is
| a. 0.4772 |
| b. 0.0228 |
| c. 0.9772 |
| d. 0.5228 |
19. A random sample of 150 people was taken from a very large population. Ninety of the people in the sample were female. The standard error of the proportion is
| a. 0.0400 |
| b. 0.2400 |
| c. 0.0016 |
| d. 0.1600 |
20. A wildlife management organization is interested in estimating the number of moose in a particular region. Organization employees divide the region into 10 sections and randomly select four sections to survey the number of moose present. What sampling method is being used?
| a. Judgment sampling |
| b. Cluster sampling |
| c. Systematic sampling |
| d. Stratified random sampling |
21. In which of the following situations should the t distribution be used?
| a. When the population is not normally distributed |
| b. Only when the population mean is 0 |
| c. When the sample size is less than 30 |
| d. When the sample standard deviation is used to estimate the population standard deviation |
22. In a sample of 400 voters, 360 indicated they favor the incumbent governor. The 95% confidence interval of voters not favoring the incumbent is
| a. .871 to .929. |
| b. .071 to .129. |
| c. .120 to .280. |
| d. .765 to .835. |
23. the population mean using the standard deviation of the sample, the degrees of freedom for the t distribution equals
| a. n + 1. |
| b. 2n. |
| c. n. |
| d. n – 1. |
24. For a given confidence level and when σ is known, the margin of error in a confidence interval estimate
| a. increases as the sample size increases. |
| b. is the same for all samples of the same size. |
| c. varies from sample to sample of the same size. |
| d. is independent of sample size |
25. The ability of an interval estimate to contain the value of the population parameter is described by the
| a. point estimate. |
| b. confidence level. |
| c. degrees of freedom. |
| d. precise value of the population mean μ. |
26. From a population that is normally distributed, a sample of 25 elements is selected and the standard deviation of the sample is computed. For the interval estimation of μ, the proper distribution to use is the
| a. t distribution with 26 degrees of freedom. |
| b. normal distribution. |
| c. t distribution with 24 degrees of freedom. |
| d. t distribution with 25 degrees of freedom. |
27. To compute the necessary sample size for an interval estimate of a population proportion, all of the following procedures are recommended when p is unknown except
| a. use the sample proportion from a previous study. |
| b. use 1.0 as an estimate. |
| c. use judgment or a best guess. |
| d. use the sample proportion from a preliminary sample |
28. In interval estimation, as the sample size becomes larger, the interval estimate
| a. becomes narrower. |
| b. remains the same, because the mean is not changing. |
| c. becomes wider. |
| d. gets closer to 1.96. |
29. As the sample size increases, the margin of error
| a. increases. |
| b. decreases. |
| c. fluctuates depending on the mean. |
| d. stays the same. |
30. A university planner wants to determine the proportion of undergraduate students who plan to attend graduate school. She surveys 54 current students and finds that 27 would like to continue their education in graduate school. Which of the following is the correct 90% confidence interval estimate for the proportion of undergraduates who plan to attend graduate school?
| a. 0.50 to 0.75 |
| b. 26.727 to 27.273 |
| c. 0.3881 to 0.6119 |
| d. 0.3608 to 0.6392 |
31. The level of significance α
| a. is (1 – confidence coefficient). |
| b. can be any positive value. |
| c. can be any value between -1.96 to 1.96. |
| d. is always a negative value |
32. A sample of 75 information systems managers had an average hourly income of $40.75 with a standard deviation of $7.00. If we want to determine a 95% confidence interval for the average hourly income of the population, the value of t is
| a. 1.28. |
| b. 1.645. |
| c. 1.993. |
| d. 1.96 |
33. The use of the normal probability distribution as an approximation of the sampling distribution of p̄ is based on the condition that both np and n(1 – p) equal or exceed
| a. .05. |
| b. 5. |
| c. 30. |
| d. 10. |
34. In a random sample of 144 observations, p̄ = .6. The 95% confidence interval for p is
| a. .52 to .68. |
| b. .55 to .65. |
| c. .50 to .70. |
| d. .14 to .20. |
35. When s is used to estimate σ, the margin of error is computed by using the
| a. mean of the sample. |
| b. mean of the population. |
| c. normal distribution. |
| d. t distribution. |
36. In developing an interval estimate, if the population standard deviation is unknown
| a. the standard deviation is arrived at using the range. |
| b. it is impossible to develop the interval estimate. |
| c. the sample standard deviation must be used. |
| d. it is assumed that the population standard deviation is 1. |
37. A random sample of 64 students at a university showed an average age of 25 years and a sample standard deviation of 2 years. The 98% confidence interval for the true average age of all students in the university is
| a. 23.0 to 27.0. |
| b. 20.0 to 30.0. |
| c. 20.5 to 29.5. |
| d. 24.4 to 25.6. |
38. A population has a standard deviation of 50. A random sample of 100 items from this population is selected. The sample mean is determined to be 600. At 95% confidence, the margin of error is
| a. 8.3. |
| b. 9.8. |
| c. 8.225. |
| d. 9.92. |
39. A random sample of 30 varieties of cereal was selected. The average number of calories per serving for these cereals is 
= 120. Assuming that σ = 10, find a 95% confidence interval for the mean number of calories, μ, in a serving of cereal.
| a. 115.30 to 124.70 |
| b. 118.00 to 122.00 |
| c. 117.00 to 123.00 |
| d. 116.42 to 123.58 |
40. The degrees of freedom associated with a t distribution are a function of the
| a. area in the upper tail. |
| b. confidence coefficient. |
| c. sample standard deviation. |
| d. sample size. |
41. The t distribution should be used whenever
| a. the population is not normally distributed. |
| b. the sample standard deviation is used to estimate the population standard deviation. |
| c. the sample size is less than 30. |
| d. the population standard deviation is known |
42. random sample of 50 customers. The average amount spent by these 50 customers was $110. It is known that the standard deviation of the amount spent by all customers is $10.60. If the confidence coefficient is increased from 0.95 to 0.99, the standard error of the mean will
| a. double in size. |
| b. remain unchanged. |
| c. increase. |
| d. decrease. |
43. The probability that the interval estimation procedure will generate an interval that does not contain the actual value of the population parameter being estimated is the
| a. margin of error. |
| b. proportion estimate. |
| c. same as α. |
| d. confidence coefficient |
44. The margin of error in an interval estimate of the population mean is a function of all of the following except
| a. variability of the population. |
| b. sample mean. |
| c. sample size. |
| d. α. |
45. The manager of a grocery store has taken a random sample of 100 customers. The average length of time it took these 100 customers to check out was 3 minutes. It is known that the standard deviation of the population of checkout times is 1 minute. The standard error of the mean equals
| a. .010. |
| b. .100. |
| c. 1.000. |
| d. .001. |
46. The owners of an amusement park selected a random sample of 200 days and recorded the number of park patrons with annual passes who visited the park on each selected day. They computed a 90% confidence interval for the number of patrons with annual passes who visit the park daily. How would you interpret the 90% confidence interval of (35, 51)?
| a. There is a 90% chance that the population mean number of patrons with annual passes who are in the park on any given day is between 35 and 51. |
| b. There is a 90% chance that the sample percentage of park patrons with annual passes is contained in the interval 35 to 51. |
| c. The method used to calculate the confidence interval has a 90% chance of producing an interval that captures the population mean number of annual pass holders in the park on any given day. |
| d. Ten percent of the population of annual pass holders visit the park on any given day. |
47. The manager of a grocery store has taken a random sample of 100 customers. The average length of time it took these 100 customers to check out was 3 minutes. It is known that the standard deviation of the population of checkout times is 1 minute. The 95% confidence interval for the true average checkout time (in minutes) is
| a. 2.804 to 3.196. |
| b. 2.5 to 3.5. |
| c. 1 to 5. |
| d. 1.36 to 4.64. |
48. A random sample of 30 varieties of cereal was selected. The average number of calories per serving for these cereals is = 120. Assuming that σ = 10, find a 95% confidence interval for the mean number of calories, μ, in a serving of cereal.
| a. 116.42 to 123.58 |
| b. 117.00 to 123.00 |
| c. 118.00 to 122.00 |
| d. 115.30 to 124.70 |
49. Using α = 0.05, a confidence interval for a population proportion is determined to be 0.15 to 0.35. If the level of significance is increased, the interval for the population proportion
| a. becomes narrower. |
| b. becomes wider. |
| c. does not change. |
| d. Not enough information is provided to answer this question. |
50. A random sample of 25 employees of a local company has been taken. A 95% confidence interval estimate for the mean systolic blood pressure for all employees of the company is 123 to 139. Which of the following statements is valid?
| a. 95% of the sample of employees has a systolic blood pressure between 123 and 139. |
| b. If the sampling procedure were repeated many times, 95% of the sample means would be between 123 and 139. |
| c. 95% of the population of employees has a systolic blood pressure between 123 and 139. |
| d. If the sampling procedure were repeated many times, 95% of the resulting confidence intervals would contain the population mean systolic blood pressure. |
51. The level of significance α
| a. is (1 – confidence coefficient). |
| b. is always a negative value. |
| c. can be any positive value. |
| d. can be any value between -1.96 to 1.96. |
52. In an interval estimation for a proportion of a population, the value of z at 99.2% confidence is
| a. 2.65. |
| b. 1.645. |
| c. 2.41. |
| d. 1.96. |
53. The use of the normal probability distribution as an approximation of the sampling distribution of p̄ is based on the condition that both np and n(1 – p) equal or exceed
| a. 10. |
| b. 5. |
| c. 30. |
| d. .05. |
54. In order to estimate the average time spent per student on the computer terminals at a local university, data were collected for a sample of 81 business students over a one-week period. Assume the population standard deviation is 1.8 hours. With a .95 probability, the margin of error is approximately
| a. 1.96. |
| b. .39. |
| c. 1.64. |
| d. .20. |
55. The value added to and subtracted from a point estimate in order to develop an interval estimate of the population parameter is known as the
| a. confidence level. |
| b. parameter estimate. |
| c. margin of error. |
| d. planning value |
56. The manager of a grocery store has taken a random sample of 100 customers. The average length of time it took these 100 customers to check out was 3 minutes. It is known that the standard deviation of the population of checkout times is 1 minute. The 95% confidence interval for the true average checkout time (in minutes) is
| a. 2.804 to 3.196. |
| b. 1.36 to 4.64. |
| c. 1 to 5. |
| d. 2.5 to 3.5. |
57. To compute the necessary sample size for an interval estimate of a population proportion, all of the following procedures are recommended when p is unknown except
| a. use the sample proportion from a preliminary sample. |
| b. use the sample proportion from a previous study. |
| c. use judgment or a best guess. |
| d. use 1.0 as an estimate. |
58. In order to estimate the average electric usage per month, a sample of 81 houses was selected and the electric usage was determined. Assume a population standard deviation of 450 kilowatt-hours. At 95% confidence, the size of the margin of error is
| a. 50.00. |
| b. 98.00. |
| c. 1.96. |
| d. 42.00. |
59. The mean of the t distribution is
| a. .5. |
| b. problem specific. |
| c. 1. |
| d. 0. |
60. The t distribution should be used whenever
| a. the population is not normally distributed. |
| b. the sample size is less than 30. |
| c. the population standard deviation is known. |
| d. the sample standard deviation is used to estimate the population standard deviation. |
61. The probability that the interval estimation procedure will generate an interval that does not contain the actual value of the population parameter being estimated is the
| a. margin of error. |
| b. confidence coefficient. |
| c. same as α. |
| d. proportion estimate |
62. The general form of an interval estimate of a population mean or a population proportion is the _____ plus and minus the _____.
| a. point estimate, margin of error |
| b. population proportion, standard error |
| c. population mean, standard error |
| d. planning value, confidence coefficient |
63. The level of significance α
| a. can be any positive value. |
| b. is (1 – confidence coefficient). |
| c. is always a negative value. |
| d. can be any value between -1.96 to 1.96. |
64. In order to estimate the average time spent per student on the computer terminals at a local university, data were collected for a sample of 81 business students over a one-week period. Assume the population standard deviation is 1.8 hours. With a .95 probability, the margin of error is approximately
| a. 1.64. |
| b. .39. |
| c. .20. |
| d. 1.96. |
65. In order to estimate the average electric usage per month, a sample of 81 houses was selected and the electric usage was determined. Assume a population standard deviation of 450 kilowatt-hours. If the sample mean is 1858 kWh, the 95% confidence interval estimate of the population mean is
| a. 1758 to 1958 kWh. |
| b. 1760 to 1956 kWh. |
| c. 1776 to 1940 kWh. |
| d. 1729 to 1987 kWh. |
66. From a population with a variance of 900, a sample of 225 items is selected. At 95% confidence, the margin of error is
| a. 15. |
| b. 3.92. |
| c. 4. |
| d. 2.0. |
67. The z value for a 97.8% confidence interval estimation is
| a. 2.29. |
| b. 1.96. |
| c. 2.00. |
| d. 2.02. |
68. A machine that produces a major part for an airplane engine is monitored closely. In the past, 10% of the parts produced would be defective. With a .95 probability, the sample size that needs to be taken if the desired margin of error is .04 or less is
| a. 110. |
| b. 216. |
| c. 111. |
| d. 217. |
69. The manager of a grocery store has taken a random sample of 100 customers. The average length of time it took these 100 customers to check out was 3 minutes. It is known that the standard deviation of the population of checkout times is 1 minute. The standard error of the mean equals
| a. .100. |
| b. 1.000. |
| c. .001. |
| d. .010. |
70. A random sample of 64 SAT scores of students applying for merit scholarships showed an average of 1400 with a standard deviation of 240. If we want to provide a 95% confidence interval for the population mean SAT score, the degrees of freedom for reading the t value is
| a. 63. |
| b. 60. |
| c. 61. |
| d. 62. |
71. A probability sampling method in which we randomly select one of the first k elements and then select every kth element thereafter is
| a. cluster sampling. |
| b. systematic sampling. |
| c. convenience sampling. |
| d. stratified random sampling. |
72. The purpose of statistical inference is to provide information about the
| a. population based upon information contained in the sample. |
| b. sample based upon information contained in the population. |
| c. mean of the sample based upon the mean of the population. |
| d. population based upon information contained in the population. |
73. All of the following are true about the standard error of the mean except
| a. its value is influenced by the standard deviation of the population. |
| b. it is larger than the standard deviation of the population. |
| c. it decreases as the sample size increases. |
| d. it measures the variability in sample means |
74. The sample mean is the point estimator of
| a. p̄ |
| b. x̄ |
| c. σ |
| d. μ |
75. Random samples of size 36 are taken from an infinite population whose mean and standard deviation are 20 and 15, respectively. The distribution of the population is unknown. The mean and the standard error of the mean are
| a. 20 and 15 |
| b. 36 and 15 |
| c. 20 and 2.5 |
| d. 20 and 0.417 |
76. A sample of 92 observations is taken from an infinite population. The sampling distribution of x̄ is approximately
| a. normal because of the central limit theorem. |
| b. normal because the sample size is small in comparison to the population size. |
| c. normal because x̄ is always approximately normally distributed. |
| d. None of these alternatives are correct |
77. For a population with any distribution, the form of the sampling distribution of the sample mean is
| a. always normal for large sample sizes. |
| b. always normal for all sample sizes. |
| c. sometimes normal for all sample sizes. |
| d. sometimes normal for large sample sizes. |
78. A subset of a population selected to represent the population is
| a. a small population. |
| b. a parameter. |
| c. a subset. |
| d. a sample. |
79. A subset of a population selected to represent the population is
| a. a small population. |
| b. a parameter. |
| c. a subset. |
| d. a sample. |
80. The manager of a grocery store has taken a random sample of 100 customers. The average length of time it took these 100 customers to check out was 3 minutes. It is known that the standard deviation of the population of checkout times is 1 minute. With a .95 probability, the sample mean will provide a margin of error of
| a. .10. |
| b. .196. |
| c. 1.64. |
| d. 1.96. |
81. A random sample of 49 statistics examinations was taken. The average score, in the sample, was 84 with a variance of 12.25. The 95% confidence interval for the average examination score of the population of the examinations is
| a. 77.40 to 86.60. |
| b. 80.48 to 87.52. |
| c. 82.99 to 85.01. |
| d. 68.00 to 100.00. |
82. A sample of 200 elements from a population with a known standard deviation is selected. For an interval estimation of μ, the proper distribution to use is the
| a. normal distribution. |
| b. t distribution with 201 degrees of freedom. |
| c. t distribution with 199 degrees of freedom. |
| d. t distribution with 200 degrees of freedom. |
83. A random sample of 25 employees of a local company has been taken. A 95% confidence interval estimate for the mean systolic blood pressure for all employees of the company is 123 to 139. Which of the following statements is valid?
| a. If the sampling procedure were repeated many times, 95% of the resulting confidence intervals would contain the population mean systolic blood pressure. |
| b. 95% of the sample of employees has a systolic blood pressure between 123 and 139. |
| c. 95% of the population of employees has a systolic blood pressure between 123 and 139. |
| d. If the sampling procedure were repeated many times, 95% of the sample means would be between 123 and 139 |
84. From a population that is not normally distributed and whose standard deviation is not known, a sample of 6 items is selected to develop an interval estimate for the mean of the population (μ).
| a. The sample size must be increased. |
| b. The normal distribution can be used. |
| c. The t distribution with 5 degrees of freedom must be used. |
| d. The t distribution with 6 degrees of freedom must be used. |
85. The t value for a 95% confidence interval estimation with 24 degrees of freedom is
| a. 1.711. |
| b. 2.064. |
| c. 2.069. |
| d. 2.492. |
86. We are interested in conducting a study in order to determine the percentage of voters in a city who would vote for the incumbent mayor. What is the minimum sample size needed to estimate the population proportion with a margin of error not exceeding 4% at 95% confidence?
| a. 601 |
| b. 600 |
| c. 626 |
| d. 625 |
87. The use of the normal probability distribution as an approximation of the sampling distribution of p̄ is based on the condition that both np and n(1 – p) equal or exceed
| a. .05. |
| b. 10. |
| c. 30. |
| d. 5. |
88. It is known that the population variance equals 484. With a .95 probability, the sample size that needs to be taken if the desired margin of error is 5 or less is
| a. 190. |
| b. 74. |
| c. 189. |
| d. 75. |
89. A random sample of 121 bottles of cologne showed an average content of 4 ounces. It is known that the standard deviation of the contents (i.e., of the population) is 0.22 ounces. The point estimate of the mean content of the bottles is
| a. 0.02 |
| b. 121 |
| c. 0.22 |
| d. 4 |
90. The number of simple random samples of size 20 that can be selected from a finite population of size 25 is _____.
| a. 20 |
| b. 53,130 |
| c. 1 |
| d. 120 |
91. The population we want to make inferences about is the
| a. frame. |
| b. target population. |
| c. finite population. |
| d. sampled population. |
92. A random sample of 121 bottles of cologne showed an average content of 4 ounces. It is known that the standard deviation of the contents (i.e., of the population) is 0.22 ounces. The standard error of the mean equals
| a. 0.0331 |
| b. 0.3636 |
| c. 0.0200 |
| d. 4.000 |
93. The following data was collected from a simple random sample of a population.
| 13 | 15 | 14 | 16 | 12 |
If the population consisted of 10 elements, how many different random samples of size 6 could be drawn from the population?
| a. 362880 |
| b. 60 |
| c. 3024 |
| d. 210 |
94. Suppose candidate A for a town council seat receives 43% of the votes in an election. As voters leave the polls, they are asked who they voted for. What is the probability that less than 40% of the 80 voters surveyed indicate they voted for candidate A? Assume an infinite population.
| a. .1368 |
| b. .7061 |
| c. .2939 |
| d. .8632 |
95. The probability distribution of all possible values of the sample mean x̄ is
| a. the probability density function of x̄. |
| b. the grand mean, since it considers all possible values of the sample mean. |
| c. one, since it considers all possible values of the sample mean. |
| d. the sampling distribution of x̄. |
96. Parameters are
| a. the averages taken from a sample. |
| b. numerical characteristics of either a sample or a population. |
| c. numerical characteristics of a population. |
| d. numerical characteristics of a sample. |
97. A probability distribution of all possible values of a sample statistic is known as
| a. a sampling distribution. |
| b. a parameter. |
| c. simple random sampling. |
| d. a sample statistic. |
98. Suppose candidate A for a town council seat receives 43% of the votes in an election. As voters leave the polls, they are asked who they voted for. What is the probability that less than 40% of the 80 voters surveyed indicate they voted for candidate A? Assume an infinite population.
| a. .8632 |
| b. .2939 |
| c. .1368 |
| d. .7061 |
99. How many different samples of size 3 can be taken from a finite population of size 10?
| a. 30 |
| b. 1,000 |
| c. 720 |
| d. 120 |
100. As a rule of thumb, the sampling distribution of the sample proportions can be approximated by a normal probability distribution whenever
| a. n ≥ 30 and (1 – p) = 0.5. |
| b. np ≥5, n ≥30. |
| c. np ≥5 and n(1-p) ≥5. |
| d. None of these alternatives are correct. |
101. In a local university, 40% of the students live in the dormitories. A random sample of 80 students is selected for a particular study. The probability that the sample proportion (the proportion living in the dormitories) is at least 0.30 is
| a. 0.9328 |
| b. 0.9664 |
| c. 0.0336 |
| d. 0.4664 |
102. In a local university, 40% of the students live in the dormitories. A random sample of 80 students is selected for a particular study. The probability that the sample proportion (the proportion living in the dormitories) is at least 0.30 is
| a. 0.9328 |
| b. 0.9664 |
| c. 0.0336 |
| d. 0.4664 |
103. The CEO of a large corporation is interested in the average salary of all managers for his large corporation. A sample of 500 managers found the average salary to be $56,500. Which of the following statements is correct?
| a. The value $56,500 is a parameter. |
| b. The population size is 500 managers. |
| c. The average salary for all the managers will also be $56,500. |
| d. The average salary for the 500 managers can be used to estimate the average salary for all the managers. |
104. The proportion of students at a university who pass a biology class is p = .86. If 50 students are randomly selected, what is the probability that at least 75% of them have passed the class?
| a. .9638 |
| b. .9875 |
| c. .0362 |
| d. .0125 |
105. Given the sampling distribution of the sample mean shown here, which of the following values is a reasonable estimate for the population mean?
| a. 280 |
| b. 300 |
| c. .27 |
| d. 320 |
106. Sampling distribution of x̄ is the
| a. probability distribution of the sample proportion. |
| b. mean of the sample. |
| c. mean of the population. |
| d. probability distribution of the sample mean. |
107. Which of the following sampling methods does not lead to probability samples?
| a. Stratified sampling |
| b. Cluster sampling |
| c. Systematic sampling |
| d. Convenience sampling |
108. A single numerical value used as an estimate of a population parameter is known as
| a. a parameter. |
| b. a population parameter. |
| c. a mean estimator. |
| d. a point estimate. |
109. A single numerical value used as an estimate of a population parameter is known as
| a. a parameter. |
| b. a population parameter. |
| c. a mean estimator. |
| d. a point estimate. |
110. A sample of 75 information systems managers had an average hourly income of $40.75 with a standard deviation of $7.00. The standard error of the mean is
| a. 1.611. |
| b. .8083. |
| c. 7.0. |
| d. 80.83. |
111. Which of the following is not required when computing the sample size for an interval estimate of the population mean?
| a. Population mean |
| b. Population standard deviation |
c.  |
| d. Margin of error the researcher is willing to accept |
112. We are interested in conducting a study in order to determine the percentage of voters in a city who would vote for the incumbent mayor. What is the minimum sample size needed to estimate the population proportion with a margin of error not exceeding 4% at 95% confidence?
| a. 601 |
| b. 600 |
| c. 626 |
| d. 625 |
113. From a population that is normally distributed, a sample of 25 elements is selected and the standard deviation of the sample is computed. For the interval estimation of μ, the proper distribution to use is the
| a. t distribution with 25 degrees of freedom. |
| b. normal distribution. |
| c. t distribution with 24 degrees of freedom. |
| d. t distribution with 26 degrees of freedom. |
114. A population has a standard deviation of 50. A random sample of 100 items from this population is selected. The sample mean is determined to be 600. At 95% confidence, the margin of error is
| a. 8.225. |
| b. 8.3. |
| c. 9.92. |
| d. 9.8. |
115. Using an α = .04, a confidence interval for a population proportion is determined to be .65 to .75. For the same data, if α is decreased, the confidence interval for the population proportion
| a. uses a zero margin of error. |
| b. becomes narrower. |
| c. remains the same. |
| d. becomes wider |
116. In order to estimate the average electric usage per month, a sample of 81 houses was selected and the electric usage was determined. Assume a population standard deviation of 450 kilowatt-hours. The standard error of the mean is
| a. 450. |
| b. 500. |
| c. 81. |
| d. 50. |
117. The t distribution is a family of similar probability distributions, with each individual distribution depending on a parameter known as the
| a. standard deviation. |
| b. sample size. |
| c. degrees of freedom. |
| d. finite correction factor |
118. The degrees of freedom associated with a t distribution are a function of the
| a. area in the upper tail. |
| b. sample standard deviation. |
| c. confidence coefficient. |
| d. sample size. |
119. From a population that is not normally distributed and whose standard deviation is not known, a sample of 6 items is selected to develop an interval estimate for the mean of the population (μ).
| a. The t distribution with 5 degrees of freedom must be used. |
| b. The normal distribution can be used. |
| c. The t distribution with 6 degrees of freedom must be used. |
| d. The sample size must be increased. |
120. The manager of a department store wants to determine the proportion of customers who use the store’s credit card when making a purchase. What sample size should he select so that at 96% confidence the error will not be more than 10%?
| a. 106 |
| b. 76 |
| c. 1 |
| d. There is not enough information given to determine the sample size. |
121. Using an α = .04, a confidence interval for a population proportion is determined to be .65 to .75. For the same data, if α is decreased, the confidence interval for the population proportion
| a. uses a zero margin of error. |
| b. becomes narrower. |
| c. becomes wider. |
| d. remains the same. |
122. A population has a standard deviation of 50. A random sample of 100 items from this population is selected. The sample mean is determined to be 600. At 95% confidence, the margin of error is
| a. 8.3. |
| b. 9.92. |
| c. 9.8. |
| d. 8.225. |
123. In order to estimate the average time spent per student on the computer terminals at a local university, data were collected for a sample of 81 business students over a one-week period. Assume the population standard deviation is 1.8 hours. With a .95 probability, the margin of error is approximately
| a. 1.64. |
| b. 1.96. |
| c. .20. |
| d. .39. |
124. In order to estimate the average time spent per student on the computer terminals at a local university, data were collected for a sample of 81 business students over a one-week period. Assume the population standard deviation is 1.8 hours. With a .95 probability, the margin of error is approximately
| a. 1.64. |
| b. 1.96. |
| c. .20. |
| d. .39. |
125. As the sample size increases, the margin of error
| a. decreases. |
| b. stays the same. |
| c. increases. |
| d. fluctuates depending on the mean. |
126. When s is used to estimate σ, the margin of error is computed by using the
| a. t distribution. |
| b. mean of the sample. |
| c. normal distribution. |
| d. mean of the population. |
127. What value of p should be used to compute the sample size that guarantees all estimates of proportions will meet the margin of error requirement?
| a. 0.01 |
| b. 0.25 |
| c. 1 |
| d. 0.50 |
128. We can use the normal distribution to make confidence interval estimates for the population proportion, p, when
| a. p has a normal distribution. |
| b. np ≥ 5. |
| c. both np ≥ 5 and n(1 – p) ≥ 5. |
| d. n(1 – p) ≥ 5. |
129. Which of the following must be decided by the researcher when computing the minimum sample size for an interval estimate of μ or p?
| a. Mean |
| b. Standard deviation |
| c. Degrees of freedom |
| d. Margin of error |
130. The value added to and subtracted from a point estimate in order to develop an interval estimate of the population parameter is known as the
| a. parameter estimate. |
| b. confidence level. |
| c. margin of error. |
| d. planning value. |
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