- A simple random sample of 64 observations was taken from a large population. The sample mean and the standard deviation were determined to be 320 and 120 respectively. The standard error of the mean is
| a. 40 |
| b. 15 |
| c. 1.875 |
| d. 5 |
2. 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. 8.7 and 1.94. |
| c. 36 and 8. |
| d. 36 and 1.94. |
3. How many simple random samples of size 5 can be selected from a population of size 8?
| a. 336 |
| b. 56 |
| c. 40 |
| d. 68 |
4. 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. 0.0778 |
| b. 0.9222 |
| c. 0.0568 |
| d. 0.4222 |
5. The following information was collected from a simple random sample of a population.
| 16 | 19 | 18 | 17 | 20 | 18 |
The point estimate of the mean of the population is
| a. 16 |
| b. 108 |
| c. 19.6 |
| d. 18.0 |
6. Random samples of size 100 are taken from an infinite population whose population proportion is 0.2. The mean and standard deviation of the sample proportion are
| a. 0.2 and 0.2 |
| b. 20 and .04 |
| c. 0.2 and .04 |
| d. 20 and 0.2 |
7. The sample statistic, such as x̄, s, or p̄, that provides the point estimate of the population parameter is known as
| a. a population parameter. |
| b. a point estimator. |
| c. a parameter. |
| d. a population statistic |
8. The standard deviation of p̄ is referred to as the
| a. deviated proportion. |
| b. sample mean proportion. |
| c. standard error of the proportion. |
| d. standard proportion. |
9. A sample of 25 observations is taken from an infinite population. The sampling distribution of p̄ is
| a. not normal since n < 30 |
| b. approximately normal if np > 30 and n(1-P) > 30 |
| c. approximately normal because p̄ is always normally distributed |
| d. approximately normal if np ≥ 5 and n(1-P) ≥ 5 |
10. In point estimation
| a. the mean of the population equals the mean of the sample. |
| b. data from the sample is used to estimate the sample statistic. |
| c. data from the sample is used to estimate the population parameter. |
| d. data from the population is used to estimate the population parameter |
11. 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. .765 to .835. |
| d. .120 to .280. |
12. When constructing a confidence interval for 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. |
13. To compute the necessary sample size for an interval estimate of a population mean, all of the following procedures are recommended when σ is unknown except
| a. use the estimated σ from a previous study. |
| b. use the sample standard deviation from a preliminary sample. |
| c. use judgment or a best guess. |
| d. use .5 as an estimate. |
14. If we want to provide a 95% confidence interval for the mean of a population, the confidence coefficient will be
| a. 1.645. |
| b. .95. |
| c. .485. |
| d. 1.96. |
15. A 95% confidence interval for a population mean is determined to be 100 to 120. For the same data, if the confidence coefficient is reduced to .90, the confidence interval for μ
| a. becomes 100.1 to 120.1. |
| b. becomes wider. |
| c. does not change. |
| d. becomes narrower. |
16. 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. 117.00 to 123.00 |
| b. 116.42 to 123.58 |
| c. 115.30 to 124.70 |
| d. 118.00 to 122.00 |
17. 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. 600 |
| b. 601 |
| c. 625 |
| d. 626 |
18. 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. 111. |
| b. 216. |
| c. 110. |
| d. 217. |
19. We can use the normal distribution to make confidence interval estimates for the population proportion, p, when
| a. both np ≥ 5 and n(1 – p) ≥ 5. |
| b. n(1 – p) ≥ 5. |
| c. p has a normal distribution. |
| d. np ≥ 5. |
20. The t distribution should be used whenever
| a. the sample standard deviation is used to estimate the population standard deviation. |
| b. the population standard deviation is known. |
| c. the population is not normally distributed. |
| d. the sample size is less than 30. |
21. A population has a mean of 53 and a standard deviation of 21. A sample of 49 observations will be taken. The probability that the sample mean will be greater than 57.95 is
| a. .0495 |
| b. .9505 |
| c. .4505 |
| d. 0 |
22. Whenever the population has a normal probability distribution, the sampling distribution of x̄ is a normal probability distribution for
| a. any sample size. |
| b. small sample sizes. |
| c. large sample sizes. |
| d. samples of size thirty or greater. |
23. A simple random sample of 64 observations was taken from a large population. The sample mean and the standard deviation were determined to be 320 and 120 respectively. The standard error of the mean is
| a. 15 |
| b. 40 |
| c. 1.875 |
| d. 5 |
24. 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. 0.9511 |
| b. 0.7200 |
| c. 8.3600 |
| d. 0.0347 |
25. The population being studied is usually considered ______ if it involves an ongoing process that makes listing or counting every element in the population impossible.
| a. infinite |
| b. finite |
| c. symmetric |
| d. skewed |
26. Which of the following is an example of nonprobabilistic sampling?
| a. Stratified simple random sampling |
| b. Judgment sampling |
| c. Cluster sampling |
| d. Simple random sampling |
27. 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 standard deviation of p̄, known as the standard error of the proportion is approximately
| a. 5.477 |
| b. 0.05477 |
| c. 54.77 |
| d. 0.5477 |
28. Four hundred people were asked whether gun laws should be more stringent. Three hundred said “yes,” and 100 said “no”. The point estimate of the proportion in the population who will respond “no” is
| a. 75 |
| b. 0.50 |
| c. 0.25 |
| d. 0.75 |
29. 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. Systematic sampling |
| b. Stratified random sampling |
| c. Cluster sampling |
| d. Judgment sampling |
30. A population of size 1,000 has a proportion of 0.5. Therefore, the proportion and the standard deviation of the sample proportion for samples of size 100 are
| a. 500 and 0.050 |
| b. 0.5 and 0.047 |
| c. 0.5 and 0.050 |
| d. 500 and 0.047 |
31. The sample size needed to provide a margin of error of 2 or less with a .95 probability when the population standard deviation equals 11 is
| a. 117. |
| b. 11. |
| c. 10. |
| d. 116. |
32. When s is used to estimate σ, the margin of error is computed by using the
| a. t distribution. |
| b. normal distribution. |
| c. mean of the population. |
| d. mean of the sample |
33. 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. |
34. In an interval estimation for a proportion of a population, the value of z at 99.2% confidence is
| a. 2.41. |
| b. 2.65. |
| c. 1.96. |
| d. 1.645. |
35. What is the t value for 
and 15 degrees of freedom?
| a. 2.145 |
| b. 0.691 |
| c. 2.120 |
| d. 2.131 |
36. 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. .120 to .280. |
| b. .871 to .929. |
| c. .071 to .129. |
| d. .765 to .835. |
37. An estimate of a population parameter that provides an interval of values believed to contain the value of the parameter is known as the
| a. interval estimate. |
| b. confidence level. |
| c. margin of error. |
| d. point estimate. |
38. 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 24 degrees of freedom. |
| b. t distribution with 25 degrees of freedom. |
| c. t distribution with 26 degrees of freedom. |
| d. normal distribution |
39. 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. 80.83. |
| b. 7.0. |
| c. 1.611. |
| d. .8083. |
40. The t distribution should be used whenever
| a. the population is not normally distributed. |
| b. the sample size is less than 30. |
| c. the sample standard deviation is used to estimate the population standard deviation. |
| d. the population standard deviation is known |
41. Which of the following best describes the form of the sampling distribution of the sample proportion?
| a. When standardized, it is the t distribution. |
| b. When standardized, it is exactly the standard normal distribution. |
| c. It is approximately normal as long as n ≥ 30. |
| d. It is approximately normal as long as np ≥ 5 and n(1 – p) ≥ 5. |
42. 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. 0.0778 |
| b. 0.4222 |
| c. 0.9222 |
| d. 0.0568 |
43. 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. Systematic sampling |
| b. Cluster sampling |
| c. Stratified random sampling |
| d. Judgment sampling |
44. It is impossible to construct a frame for a(n)
| a. finite population. |
| b. infinite population. |
| c. target population. |
| d. defined population |
45. 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. 0.9511 |
| b. 8.3600 |
| c. 0.0347 |
| d. 0.7200 |
46. 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. 0.0016 |
| b. 0.1600 |
| c. 0.0400 |
| d. 0.2400 |
47. A population has a mean of 300 and a standard deviation of 18. A sample of 144 observations will be taken. The probability that the sample mean will be between 297 to 303 is
| a. 0.9332. |
| b. 0.0668. |
| c. 0.4332. |
| d. 0.9544. |
48. As a rule of thumb, the sampling distribution of the sample proportions can be approximated by a normal probability distribution whenever
| a. np ≥5, n ≥30. |
| b. n ≥ 30 and (1 – p) = 0.5. |
| c. np ≥5 and n(1-p) ≥5. |
| d. None of these alternatives are correct |
49. 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. 20 and 0.417 |
| c. 36 and 15 |
| d. 20 and 2.5 |
50. The number of simple random samples of size 20 that can be selected from a finite population of size 25 is _____.
| a. 53,130 |
| b. 1 |
| c. 120 |
| d. 20 |
51. If we consider the simple random sampling process as an experiment, the sample mean is
| a. always zero. |
| b. exactly equal to the population mean. |
| c. a random variable. |
| d. always smaller than the population mean |
52. Which of the following is an example of nonprobabilistic sampling?
| a. Cluster sampling |
| b. Simple random sampling |
| c. Judgment sampling |
| d. Stratified simple random sampling |
53. The sampling distribution of the sample means
| a. is used as a point estimator of the population mean μ. |
| b. is an unbiased estimator. |
| c. is the probability distribution showing all possible values of the sample mean. |
| d. shows the distribution of all possible values of μ. |
54. A sample of 240 is selected from a finite population of 500. If the standard deviation of the population is 44, what is the standard error of the sample mean?
| a. 1.42 |
| b. 2.84 |
| c. 2.05 |
| d. 4.20 |
55. Four hundred people were asked whether gun laws should be more stringent. Three hundred said “yes,” and 100 said “no”. The point estimate of the proportion in the population who will respond “yes” is
| a. 0.25 |
| b. approximately 300 |
| c. 300 |
| d. 0.75 |
56. A population of size 1,000 has a proportion of 0.5. Therefore, the proportion and the standard deviation of the sample proportion for samples of size 100 are
| a. 0.5 and 0.047 |
| b. 500 and 0.047 |
| c. 500 and 0.050 |
| d. 0.5 and 0.050 |
57. The probability distribution of all possible values of the sample mean x̄ is
| a. the sampling distribution of x̄. |
| b. the probability density function of x̄. |
| c. one, since it considers all possible values of the sample mean. |
| d. the grand mean, since it considers all possible values of the sample mean. |
58. The population being studied is usually considered ______ if it involves an ongoing process that makes listing or counting every element in the population impossible.
| a. symmetric |
| b. skewed |
| c. finite |
| d. infinite |
59. 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. 320 and .02 |
| c. 192 and 45 |
| d. .60 and .14 |
60. 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 normal distribution can be used. |
| b. The sample size must be increased. |
| c. The t distribution with 5 degrees of freedom must be used. |
| d. The t distribution with 6 degrees of freedom must be used. |
61. If we want to provide a 95% confidence interval for the mean of a population, the confidence coefficient will be
| a. .485. |
| b. 1.96. |
| c. .95. |
| d. 1.645 |
62. When s is used to estimate σ, the margin of error is computed by using the
| a. t distribution. |
| b. normal distribution. |
| c. mean of the sample. |
| d. mean of the population. |
63. 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. |
64. 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. 9.92. |
| c. 9.8. |
| d. 8.3. |
65. 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. 1.96. |
| d. 1.993. |
66. 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. 7.0. |
| b. 80.83. |
| c. 1.611. |
| d. .8083. |
67. To compute the minimum sample size for an interval estimate of μ, we must first determine all of the following except
| a. population standard deviation. |
| b. degrees of freedom. |
| c. confidence level. |
| d. desired margin of error. |
68. A sample of 75 information systems managers had an average hourly income of $40.75 with a standard deviation of $7.00. The value of the margin of error at 95% confidence is
| a. 7.00. |
| b. .81. |
| c. 1.61. |
| d. 80.83. |
69. A sample of 75 information systems managers had an average hourly income of $40.75 with a standard deviation of $7.00. The 95% confidence interval for the average hourly wage (in $) of all information system managers is
| a. 39.40 to 42.10. |
| b. 37.54 to 43.96. |
| c. 38.61 to 42.89. |
| d. 39.14 to 42.36. |
70. The following random sample from a population whose values were normally distributed was collected.
| 10 | 8 | 11 | 11 |
The 95% confidence interval for μ is
| a. 7.75 to 12.25. |
| b. 8.00 to 10.00. |
| c. 9.25 to 10.75. |
| d. 8.52 to 11.48. |
71. To compute the necessary sample size for an interval estimate of a population mean, all of the following procedures are recommended when σ is unknown except
| a. use the sample standard deviation from a preliminary sample. |
| b. use judgment or a best guess. |
| c. use .5 as an estimate. |
| d. use the estimated σ from a previous study |
72. 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. 24.4 to 25.6. |
| b. 23.0 to 27.0. |
| c. 20.0 to 30.0. |
| d. 20.5 to 29.5. |
73.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. remains the same. |
| b. uses a zero margin of error. |
| c. becomes narrower. |
| d. becomes wider. |
74. 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 size. |
| d. sample standard deviation. |
75. 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. |
76. 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. degrees of freedom. |
| c. finite correction factor. |
| d. sample size. |
77. A random sample of 64 SAT scores of students applying for merit scholarships showed an average of 1400 with a standard deviation of 240. The t value needed to develop the 95% confidence interval for the population mean SAT score is
| a. 1.96. |
| b. 1.645. |
| c. 1.998. |
| d. 1.28 |
78. 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. Margin of error |
| c. Degrees of freedom |
| d. Standard deviation |
79. We can use the normal distribution to make confidence interval estimates for the population proportion, p, when
| a. both np ≥ 5 and n(1 – p) ≥ 5. |
| b. p has a normal distribution. |
| c. np ≥ 5. |
| d. n(1 – p) ≥ 5. |
80. A sample statistic is an unbiased estimator of the population parameter when
| a. the standard deviation of the sampling distribution is less than 5. |
| b. the expected value of the sample statistic is equal to the value of the population parameter. |
| c. the data was used to estimate a population mean. |
| d. the mean of the sampling distribution has a z-score of zero. |
81. The expected value of equals the mean of the population from which the sample is drawn
| a. only if the sample size is 30 or greater. |
| b. for any sample size. |
| c. only if the sample size is 100 or greater. |
| d. only if the sample size is 50 or greater. |
82. A probability sampling method in which we randomly select one of the first k elements and then select every kth element thereafter is
| a. systematic sampling. |
| b. cluster sampling. |
| c. convenience sampling. |
| d. stratified random sampling. |
83. Which of the following is(are) point estimator(s)?
| a. μ |
| b. σ |
| c. α |
| d. s |
84. 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. 8.3600 |
| b. 0.0347 |
| c. 0.9511 |
| d. 0.7200 |
85. A simple random sample of 5 observations from a population containing 400 elements was taken, and the following values were obtained.
| 12 | 18 | 19 | 20 | 21 |
A point estimate of the mean is
| a. 10 |
| b. 400 |
| c. 18 |
| d. 20 |
86. 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. .8632 |
| c. .2939 |
| d. .7061 |
87. Suppose the salaries of university professors are approximately normally distributed with a mean of $65,000 and a standard deviation of $7,000. If a random sample of size 25 is taken and the mean is calculated, what is the probability that the mean value will be between $62,500 and $64,000?
| a. .2005 |
| b. .1465 |
| c. .0827 |
| d. .0371 |
88. 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 standard deviation of p̄, known as the standard error of the proportion is approximately
| a. 0.5477 |
| b. 5.477 |
| c. 54.77 |
| d. 0.05477 |
89. A probability distribution of all possible values of a sample statistic is known as
| a. a parameter. |
| b. a sampling distribution. |
| c. a sample statistic. |
| d. simple random sampling. |
90. A population consists of 8 items. The number of different simple random samples of size 3 that can be selected from this population is
| a. 56 |
| b. 128 |
| c. 24 |
| d. 512 |
91. The following information was collected from a simple random sample of a population.
| 16 | 19 | 18 | 17 | 20 | 18 |
The point estimate of the population standard deviation is
| a. 1.667 |
| b. 1.414 |
| c. 2.000 |
| d. 1.291 |
92. 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. Stratified random sampling |
| b. Systematic sampling |
| c. Judgment sampling |
| d. Cluster sampling |
93. The number of simple random samples of size 20 that can be selected from a finite population of size 25 is _____.
| a. 120 |
| b. 1 |
| c. 53,130 |
| d. 20 |
94. The purpose of statistical inference is to provide information about the
| a. mean of the sample based upon the mean of the population. |
| b. population based upon information contained in the sample. |
| c. population based upon information contained in the population. |
| d. sample based upon information contained in the population. |
95. Cluster sampling is
| a. a nonprobability sampling method. |
| b. the same as convenience sampling. |
| c. a systematic sampling method. |
| d. a probability sampling method. |
96. A single numerical value used as an estimate of a population parameter is known as
| a. a parameter. |
| b. a point estimate. |
| c. a mean estimator. |
| d. a population parameter. |
97. If we select simple random samples of size 2 from the given data, what is the probability of any of the five employees being selected first?
| a. .50 |
| b. .40 |
| c. .10 |
| d. .20 |
98. The extent of the sampling error might be affected by all of the following factors except
| a. the variability of the population. |
| b. the expected value of the sample statistic. |
| c. the sample size. |
| d. the sampling method used |
99. 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. If the sample mean is 9 hours, then the 95% confidence interval is
| a. 7.36 to 10.64 hours. |
| b. 7.04 to 10.96 hours. |
| c. 7.80 to 10.20 hours. |
| d. 8.61 to 9.39 hours. |
100. A random sample of 144 observations has a mean of 20, a median of 21, and a mode of 22. The population standard deviation is known to equal 4.8. The 95.44% confidence interval for the population mean is
| a. 15.2 to 24.8. |
| b. 19.20 to 20.80. |
| c. 21.2 to 22.8. |
| d. 19.216 to 20.784. |
101. 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. 1776 to 1940 kWh. |
| b. 1729 to 1987 kWh. |
| c. 1758 to 1958 kWh. |
| d. 1760 to 1956 kWh. |
102. A 95% confidence interval and a 99% confidence interval are computed from the same set of data. Which of the following statements is correct?
| a. The intervals have the same width. |
| b. You need to know the sample size, n, and the standard deviation to determine which interval is wider. |
| c. The 99% confidence interval is wider. |
| d. The 95% confidence interval is wider. |
103. As the number of degrees of freedom for a t distribution increases, the difference between the t distribution and the standard normal distribution
| a. fluctuates. |
| b. stays the same. |
| c. becomes smaller. |
| d. becomes larger. |
104. A random sample of 64 SAT scores of students applying for merit scholarships showed an average of 1400 with a standard deviation of 240. The 95% confidence interval for the population mean SAT score is
| a. 1340.06 to 1459.94. |
| b. 1320.32 to 1479.68. |
| c. 1341.20 to 1458.80. |
| d. 1349.93 to 1450.07. |
105. 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 |
106. Which of the following is not required when computing the sample size for an interval estimate of the population mean?
| a. Population mean |
b.  |
| c. Margin of error the researcher is willing to accept |
| d. Population standard deviation |
107. A random sample of 15 employees was selected. The average age in the sample was 31 years with a variance of 49 years. Assuming ages are normally distributed, the 98% confidence interval for the population average age is _____.
| a. 25.62 to 36.38 |
| b. 27.82 to 34.18 |
| c. 11.54 to 18.46 |
| d. 26.26 to 35.74 |
108. 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. 9.92. |
| c. 9.8. |
| d. 8.3. |
109. The t distribution should be used whenever
| a. the sample size is less than 30. |
| b. the population is not normally distributed. |
| c. the sample standard deviation is used to estimate the population standard deviation. |
| d. the population standard deviation is known |
110. We are interested in conducting a study to determine the percentage of voters of a state would vote for the incumbent governor. What is the minimum sample size needed to estimate the population proportion with a margin of error of .05 or less at 95% confidence?
| a. 200. |
| b. 385. |
| c. 58. |
| d. 100 |
111. If we change a 95% confidence interval estimate to a 99% confidence interval estimate, we can expect the
| a. width of the confidence interval to decrease. |
| b. width of the confidence interval to remain the same. |
| c. width of the confidence interval to increase. |
| d. sample size to increase. |
112. 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. .39. |
| b. 1.64. |
| c. 1.96. |
| d. .20. |
113. 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. If the sample mean is 9 hours, then the 95% confidence interval is
| a. 7.36 to 10.64 hours. |
| b. 7.04 to 10.96 hours. |
| c. 7.80 to 10.20 hours. |
| d. 8.61 to 9.39 hours. |
114. As the degrees of freedom increase, the t distribution approaches the
| a. exponential distribution. |
| b. p distribution. |
| c. normal distribution. |
| d. uniform distribution. |
115. In which of the following situations should the t distribution be used?
| a. When the sample standard deviation is used to estimate the population standard deviation |
| b. When the sample size is less than 30 |
| c. When the population is not normally distributed |
| d. Only when the population mean is 0 |
116. The following random sample from a population whose values were normally distributed was collected.
| 10 | 8 | 11 | 11 |
The 95% confidence interval for μ is
| a. 7.75 to 12.25. |
| b. 9.25 to 10.75. |
| c. 8.52 to 11.48. |
| d. 8.00 to 10.00. |
117. 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. 189. |
| b. 190. |
| c. 74. |
| d. 75. |
118. The sampling error is the
| a. same as the standard error of the mean. |
| b. error caused by selecting a bad sample. |
| c. difference between the value of the sample mean and the value of the population mean. |
| d. standard deviation multiplied by the sample size. |
119. A probability distribution of all possible values of a sample statistic is known as
| a. a sampling distribution. |
| b. a sample statistic. |
| c. a parameter. |
| d. simple random sampling |
120. A simple random sample of 100 observations was taken from a large population. The sample mean and the standard deviation were determined to be 80 and 12 respectively. The standard error of the mean is
| a. 8.00 |
| b. 0.80 |
| c. 0.12 |
| d. 1.20 |
121. Doubling the size of the sample will
| a. reduce the standard error of the mean to approximately 70% of its current value. |
| b. have no effect on the standard error of the mean. |
| c. reduce the standard error of the mean to one-half its current value. |
| d. double the standard error of the mean. |
122. The standard error of the proportion will become larger as
| a. n increases. |
| b. p approaches .5. |
| c. p approaches 1. |
| d. p approaches 0. |
123. 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 standard deviation of p̄, known as the standard error of the proportion is approximately
| a. 5.477 |
| b. 0.5477 |
| c. 54.77 |
| d. 0.05477 |
124. The closer the sample mean is to the population mean,
| a. the smaller the sampling error. |
| b. the larger the sampling error. |
| c. the sampling error equals 1. |
| d. None of these alternatives are correct |
125. The probability distribution of all possible values of the sample mean x̄ is
| a. the grand mean, since it considers all possible values of the sample mean. |
| b. the sampling distribution of x̄. |
| c. one, since it considers all possible values of the sample mean. |
| d. the probability density function of x̄. |
126. From a population of 500 elements, a sample of 225 elements is selected. It is known that the variance of the population is 900. The standard error of the mean is approximately
| a. 2 |
| b. 30 |
| c. 1.1022 |
| d. 1.4847 |
127. It is impossible to construct a frame for a(n)
| a. finite population. |
| b. infinite population. |
| c. target population. |
| d. defined population |
128. From a population of 200 elements, a sample of 49 elements is selected. It is determined that the sample mean is 56 and the sample standard deviation is 14. The standard error of the mean is
| a. 3 |
| b. greater than 2 |
| c. 2 |
| d. less than 2 |
129. A sample of 24 observations is taken from a population that has 150 elements. The sampling distribution of x̄ is
| a. approximately normal because of the central limit theorem. |
| b. normal if the population is normally distributed. |
| c. approximately normal because x̄ is always approximately normally distributed. |
| d. approximately normal because the sample size is large in comparison to the population size. |
130. A population of size 1,000 has a proportion of 0.5. Therefore, the proportion and the standard deviation of the sample proportion for samples of size 100 are
| a. 0.5 and 0.050 |
| b. 0.5 and 0.047 |
| c. 500 and 0.047 |
| d. 500 and 0.050 |
131. The following information was collected from a simple random sample of a population.
| 16 | 19 | 18 | 17 | 20 | 18 |
The point estimate of the population standard deviation is
| a. 1.667 |
| b. 1.291 |
| c. 1.414 |
| d. 2.000 |
132. For a population with any distribution, the form of the sampling distribution of the sample mean is
| a. sometimes normal for all sample sizes. |
| b. sometimes normal for large sample sizes. |
| c. always normal for all sample sizes. |
| d. always normal for large sample sizes. |
133. Which of the following is an example of nonprobabilistic sampling?
| a. Judgment sampling |
| b. Stratified simple random sampling |
| c. Cluster sampling |
| d. Simple random sampling |
134. As the sample size increases, the
| a. population mean increases. |
| b. standard deviation of the population decreases. |
| c. standard error of the mean increases. |
| d. standard error of the mean decreases |
135. The purpose of statistical inference is to provide information about the
| a. population based upon information contained in the population. |
| 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 sample. |
136. 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. In this problem the 0.22 is
| a. the standard error of the mean. |
| b. a statistic. |
| c. a parameter. |
| d. the average content of colognes in the long run. |
137. A population has a mean of 180 and a standard deviation of 24. A sample of 64 observations will be taken. The probability that the sample mean will be between 183 and 186 is
| a. 0.8185 |
| b. 0.3413 |
| c. 0.4772 |
| d. 0.1359 |
138. The following information was collected from a simple random sample of a population.
| 16 | 19 | 18 | 17 | 20 | 18 |
The point estimate of the population standard deviation is
| a. 1.291 |
| b. 1.667 |
| c. 2.000 |
| d. 1.414 |
139. 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. .7061 |
| d. .1368 |
140. 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. 0.9772 |
| b. 0.0228 |
| c. 0.4772 |
| d. 0.5228 |
141. As the sample size increases, the
| a. standard deviation of the population decreases. |
| b. standard error of the mean increases. |
| c. standard error of the mean decreases. |
| d. population mean increases. |
142. The population being studied is usually considered ______ if it involves an ongoing process that makes listing or counting every element in the population impossible.
| a. infinite |
| b. symmetric |
| c. skewed |
| d. finite |
143. 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 population is infinite. |
| c. irrespective of the size of the sample. |
| d. whenever the sample size is less than 5% of the population size |
144. A simple random sample of size n from an infinite population of size N is to be selected. Each possible sample should have
| a. the same probability of being selected |
| b. a probability of 1/n of being selected |
| c. a probability of 1/N of being selected |
| d. a probability of N/n of being selected |
145. 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. In this problem the 0.22 is
| a. a parameter. |
| b. the standard error of the mean. |
| c. the average content of colognes in the long run. |
| d. a statistic. |
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