1. a 95% confidence interval for a population mean is determined to be 100 to 120. If the confidence coefficient is reduced to 0.90, the interval for u   becomes narrower
2. A 95% confidence interval for a population mean is determined to be 100 to 120. If the confidence coefficient is reduced to .90, the interval for μ _____.  becomes narrower
3. A bank manager wishes to estimate the average waiting time for customers in line for tellers. A random sample of 50 times is measured and the average waiting time is 5.7 minutes. The population standard deviation of waiting time is 2 minutes. Which Excel function would be used to construct a confidence interval estimate?    CONFIDENCE.NORM
4. A bank manager wishes to estimate the average waiting time for customers in line for tellers. A random sample of 50 times is measured and the average waiting time is 5.7 minutes. The population standard deviation of waiting time is 2 minutes. Which Excel function would be used to construct a confidence interval estimate?  CONFIDENCE.NORM
5. A graphical device for depicting qualitative data that have been summarized in a frequency distribution, relative frequency distribution, or percent frequency distribution is a(n)   bar graph
6. A manufacturer wants to estimate the proportion of defective items that are produced by a certain machine. A random sample of 50 is taken. Which Excel function would not be appropriate to construct a confidence interval estimate?  STDEV
7. A normal probability distribution  is a continuous probability distribution
8. A numerical measure, such as mean, computed from a population is known as a   population parameter
9. 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    19.2 to 20.8
10. 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     19.2 to 20.8
11. A random sample of 25 employees of a local company has been measured. A 95% confidence interval estimate for the mean systolic blood pressure for all company employees is 123 to 139. Which of the following statements is valid?  If the sampling procedure were repeated many times, 95% of the resulting confidence intervals would contain the population mean systolic blood pressure.
12. A random sample of 25 statistics examinations was selected. The average score in the sample was 76 with a variance of 144. Assuming the scores are normally distributed, the 99% confidence interval for the population average examination score is _____   69.29 to 82.71
13. A random sample of 25 statistics examinations was taken. The average score in the sample was 76 with a variance of 144. Assuming the scores are normally distributed, the 99% confidence interval for the population average examination score is   69.82 to 82.18
14. A random sample of 36 students at a community college showed an average age of 25 years. Assume the ages of all students at the college are normally distributed with a standard deviation of 1.8 years. The 98% confidence interval for the average age of all students at this college is  24.301 to 25.699
15. A sample of 26 elements from a normally distributed population is selected. The sample mean is 10 with a standard deviation of 4. The 95% confidence interval for μ is _____.   8.384 to 11.616
16. A simple random sample of size n from a finite population of size N is a sample selected such that each possible sample of size  n has the same probability of being selected
17. A weighted average of the value of a random variable, where the probability function provides weights is known as     the expected value
18. An auto manufacturer wants to estimate the annual income of owners of a particular model of automobile. A random sample of 200 current owners is selected. The population standard deviation is known. Which Excel function would NOT be appropriate to use to construct a confidence interval estimate?  COUNTIF
19. An estimate of a population parameter that provides an interval believed to contain the value of the parameter is known as the _____.  interval estimate
20. An interval estimate is used to estimate    a population parameter
21. An interval estimate is used to estimate _____.   a population parameter
22. An interval estimate is used to estimate _____.  population parameter
23. As the degrees of freedom increase, the t distribution approaches the _____ distribution.   Normal
24. As the degrees of freedom increase, the t distribution approaches the _____ distribution.     Normal
25. As the number of degrees of freedom for a t distribution increases, the difference between the t distribution and the standard normal distribution   becomes smaller
26. As the number of degrees of freedom for a t distribution increases, the difference between the t distribution and the standard normal distribution ___   becomes smaller
27. As the sample size increases, the margin of error    decreases
28. As the sample size increases, the margin of error   decreases
29. As the sample size increases, the margin of error _____.     Decreases
30. As the sample size increases, the margin of error _____.  Decreases
31. Categorical Data    may be either numeric or non-numeric
32. For the interval estimation of u when o- is assumed known, the proper distribution is the  standard normal distribution
33. For the interval estimation of μ when σ is assumed known, the proper distribution to use is the  standard normal distribution
34. For the interval estimation of μ when σ is assumed known, the proper distribution to use is the_____.   standard normal distribution
35. For the interval estimation of μ when σ is assumed known, the proper distribution to use is the_____.  standard normal distribution
36. From a population that is normally distributed with an unknown standard deviation, a sample of 25 elements is selected. For the interval estimation of μ, the proper distribution to use is the        t distribution with 24 degrees of freedom
37. From a population that is normally distributed with an unknown standard deviation, a sample of 25 elements is selected. For the interval estimation of u, the proper distribution to use is the              t distribution with 24 degrees of freedom
38. From a population that is normally distributed with an unknown standard deviation, a sample of 25 elements is selected. For the interval estimation of μ, the proper distribution to use is the _____.   r distribution with 24 degrees of freedom
39. From a population that is not normally distributed and whose standard deviation is not known, a sample of 50 items is selected to develop an interval estimate for μ. Which of the following statements is true?      the t distribution with 49 degrees of freedom must be used
40. If an interval estimate is said to be constructed at the 90% confidence level, the confidence coefficient would be     0.9
41. If an interval estimate is said to be constructed at the 90% confidence level, the confidence coefficient would be ___   0.9
42. If the margin of error in an interval estimate of μ is 4.6, the interval estimate equals   x +/- 4.6
43. If we change a 95% confidence interval estimate to a 99% confidence interval estimate, we can expect the _____.  width of the confidence interval to increase
44. If we want to provide a 95% confidence interval for the mean of a population, the confidence coefficient is   0.95
45. In determining an interval estimate of a population mean when σ is unknown, we use a t distribution with    n − 1 degrees of freedom
46. In determining an interval estimate of a population mean when σ is unknown, we use a t distribution with _____ degrees of freedom.  n-1
47. In determining an interval estimate of a population mean when σ is unknown, we use a t distribution with _____ degrees of freedom.  n-1
48. In determining the sample size necessary to estimate a population proportion, which of the following information is not needed? the mean of the population
49. In developing an interval estimate of the population mean, if the population standard deviation is unknown   the sample standard deviation and t distribution can be used
50. In developing an interval estimate of the population mean, if the population standard deviation is unknown ___   the sample standard deviation and t distribution can be used
51. In general, higher confidence levels provide     wider confidence intervals
52. In general, higher confidence levels provide _____.   wider confidence intervals
53. In general, higher confidence levels provide _____.  wider confidence intervals
54. It is known that the variance of a population equals 1,936. A random sample of 121 has been selected from the population. There is a .95 probability that the sample mean will provide a margin of error of _____.  7.84 or less
55. Larger values of the standard deviation result in a normal curve that is  wider and flatter
56. quantitative data     are always numeric
57. Refer to Exhibit 8-1. If the sample mean is 9 hours, then the 95% confidence interval is approximately _____.  8.74 to 9.26
58. Refer to Exhibit 8-1. The standard error of the mean is _____.  0.133
59. Refer to Exhibit 8-1. With a .95 probability, the margin of error is approximately_____. 0.26
60. Refer to Exhibit 8-2. If the confidence coefficient is reduced to .80, the standard error of the mean _____.  remains unchanged
61. Refer to Exhibit 8-2. The 95% confidence interval for the average checkout time for all customers is   2.804 to 3.196
62. Refer to Exhibit 8-2. The standard error of the mean equals _____.  0.1
63. Refer to Exhibit 8-2. With a .95 probability, the sample mean will provide a margin of error of _____.    0.196
64. Refer to Exhibit 8-3. If the sample size was 25 (other factors remain unchanged), the interval for μ would _____. become wider
65. Refer to Exhibit 8-3. If we are interested in determining an interval estimate for μ at 86.9% confidence, the z value to use is _____.  1.51
66. Refer to Exhibit 8-3. The 86.9% confidence interval for μ is _____.  57.735 to 62.265
67. Refer to Exhibit 8-3. The value to use for the standard error of the mean is _____.  1.5
68. Statistical Inference    is the process of drawing inferences about the population based on the information taken from the sample
69. the ability of an interval estimate to contain the value of the population parameter is described by the   confidence level
70. The ability of an interval estimate to contain the value of the population parameter is described by the _____.  confidence level
71. The confidence associated with an interval estimate is called the _____.  confidence level
72. The expression used to compute an interval estimate of μ may depend on any of the following factors EXCEPT   whether there is sampling error
73. The general form of an interval estimate of a population mean or population proportion is the _____ plus or minus the _____.  point estimate, margin of error
74. The mean of a sample is   computed by summing all the data values and dividing the sum by the number of items
75. The mean of the t distribution is _____.    0
76. The measure of location that is most likely to be influenced by extreme values in the data set is the   mean
77. The probability assigned to each experimental outcome must be    between zero and one
78. The probability that the interval estimation procedure will generate an interval that contains the actual value of the population parameter being estimated is the _____.     confidence coefficient
79. The probability that the interval estimation procedure will generate an interval that contains the actual value of the population parameter being estimated is the _____.   confidence coefficient
80. The sample size that guarantees all estimates of proportions will meet the margin of error requirements is computed using a planning value of p equal to _____.  0.50
81. The sampling error is the   absolute value of the difference between an unbiased point estimate and the corresponding population parameter
82. The t distribution is a family of similar probability distributions, with each individual distribution depending on a parameter known as the _____.  degrees of freedom
83. The t distribution is a family of similar probability distributions, with each individual distribution depending on a parameter known as the _____.   degrees of freedom
84. The t distribution should be used whenever _____.  the sample standard deviation is used to estimate the population standard deviation
85. The t value with a 95% confidence and 24 degrees of freedom is    2.064
86. 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 _____.     5
87. The use of the normal probability distribution as an approximation of the sampling distribution of is based on the condition that both np and n(1 – p) equal or exceed _____.  5
88. The weight of an object, measured in grams, is an example of   a continuous random variable
89. The weight of an object, measured to the nearest gram, is an example of   a discrete random variable
90. The z value for a 97.8% confidence interval estimation is _____.  2.29
91. To compute the minimum sample size for an interval estimate of μ when the population standard deviation is known, we must first determine all of the following EXCEPT ____  degrees of freedom
92. To estimate a population mean, 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 _____. 117
93. We can reduce the margin of error in an interval estimate of p by doing any of the following EXCEPT _____.  using a planningvalue p* closer to 0.5
94. We can use the normal distribution to make confidence interval estimates for the population proportion, p, when   both np > 5 and n(1-p) > 5
95. When the data are labels or names used to identify an attribute of the elements, the variable has which scale of measurement?     Nominal
96. When the level of confidence increases, the confidence interval _____.   becomes wider
97. When the results of experimentation or historical data are used to assign probability values, the method used to assign probabilities is referred to as the   relative frequency method
98. Whenever the population standard deviation is unknown, which distribution is used in developing an interval estimate for a population mean?  t distribution
99. Whenever using the t distribution in interval estimation, we must assume that _____.  a random sample was selected
100. A coal company wants to determine a 95% confidence interval estimate for the average daily tonnage of coal that it mines. Assuming the company reports that the standard deviation of daily output is 200 tons, how many days should it sample so that the margin of error will be 39.2 tons or less?    100
101.  A health club annually surveys its members. Last year, 33% of the members said they use the treadmill at least four times a week. How large a sample should be selected this year to estimate the percentage of members who use the treadmill at least four times a week? The estimate is desired to have a margin of error of 5% with a 95% level of confidence.  340
102. A local hotel wants to estimate the proportion of its guests that are from out of state. Preliminary estimates are that 45% of the hotel guests are from out-of-state.What sample size should be selected to estimate the proportion of out of state guests with a margin of error no larger than 5% and with a 95% level of confidence?  381
103. A manufacturer wants to estimate the proportion of defective items that are produced by a certain machine. A random sample of 50 items is selected. Which Excel function would NOT be appropriate to construct a confidence interval estimate?    STDEV
104. A newspaper wants to estimate the proportion of Americans who will vote for Candidate A. A random sample of 1000 voters is selected. Of the 1000 respondents, 526 say that they will vote for Candidate A. Which Excel function would be used to construct a confidence interval estimate?  NORM.S.INV
105. A random sample of 26 checking accounts at a bank showed an average daily balance of $300 and a standard deviation of $45. The balances of all checking accounts at the bank are normally distributed. Develop a 95% confidence interval estimate for the mean of the population.  $281.82 to $318.18
106. A random sample of 81 children with working mothers showed that they were absent from school an average of 6 days per term. The population standard deviation is known to be 1.8 days. Provide a 90% confidence interval for the average number of days absent per term for all children with working mothers.  5.671 to 6.329
107. A random sample of 81 students at a local university showed that they work an average of 100 hours per month. The population standard deviation is known to be 27 hours. Compute a 95% confidence interval for the mean hours per month all students at the university work.                 94.12 to 105.88
108. A real estate agent wants to estimate the mean selling price of two-bedroom homes in a particular area. She wants to estimate the mean selling price to within $10,000 with an 89.9% level of confidence. The standard deviation of selling prices is unknown but the agent estimates that the highest selling price is $1,000,000 and the lowest is $50,000. How many homes should be sampled?  1518
109. A researcher is interested in determining the average number of years employees of a company stay with the company. If past information shows a standard deviation of 7 months, what size sample should be selected so that at 95% confidence the margin of error will be 2 months or less?  48
110. A sample of 16 students from a large university is selected. The average age in the sample was 22 years with a standard deviation of 6 years. Construct a 95% confidence interval for the average age of the population. Assume the population of student ages is normally distributed.  18.8035 to 25.1965
111. A sample of 25 patients in a doctor’s office showed that they had to wait an average of 35 minutes with a standard deviation of 10 minutes before they could see the doctor. Provide a 98% confidence interval estimate for the average waiting time of all the patients who visit this doctor. Assume the population of waiting times is normally distributed   30.016 to 39.984
112. A simple random sample of 144 items resulted in a sample mean of 1080. The population standard deviation is known to be 240. Develop a 95% confidence interval for the population mean.   1040.8 to 1119.2
113. A simple random sample of 25 items from a normally distributed population resulted in a sample mean of 28 and a standard deviation of 7.5. Construct a 95% confidence interval for the population mean.  24.904 to 31.096
114. A statistician selected a sample of 16 accounts receivable and determined the mean of the sample to be $5,000 with a standard deviation of $400. She reported that the sample information indicated the mean of the population ranges from $4,739.80 to $5,260.20. She did not report what confidence coefficient she had used. Based on the above information, determine the confidence coefficient that was used   0.98
115. As the degrees of freedom increase, the t distribution approaches the _____ distribution.  Normal
116. Computing the necessary sample size for an interval estimate of a population proportion requires a planning value for . In case of any uncertainty about an appropriate planning value, we know the value that will provide the largest sample size for a given level of confidence and a given margin of error is  0.50
117. For inventory purposes, a grocery store manager wants to estimate the mean number of pounds of cat food sold per month. The estimate is desired to be within 10 pounds with a 95% level of confidence. A pilot study provided a standard deviation of 27.6 pounds. How many months should be sampled?  30
118. For which of the following values of p is the value of P(1 − p) maximized?    p=0.50
119. If the standard deviation of the lifetimes of vacuum cleaners is estimated to be 300 hours, what sample size must be selected in order to be 97% confident that the margin of error will not exceed 40 hours?  265
120. In determining the sample size necessary to estimate a population proportion, which of the following is NOT needed?   the mean of the population
121. It is known that the population variance equals 484. With a .95 probability, the sample size that needs to be taken to estimate the population mean if the desired margin of error is 5 or less is  75
122. The degrees of freedom associated with a t distribution are a function of the _____.  sample size
123. The general form of an interval estimate of a population mean or population proportion is the _____ plus or minus the _____.   point estimate, margin of error
124. The manager of a department store wants to determine what proportion of people who enter the store use the store’s credit card for their purchases. What size sample should he take so that at 99% confidence the error will not be more than 8%?  260
125. The margin of error in an interval estimate of the population mean is a function of all of the following EXCEPT _____.     sample mean
126. The monthly starting salaries of students who receive an MBA degree have a standard deviation of $110. What size sample should be selected to obtain a .95 probability of estimating the mean monthly income within $20 or less?  117
127. The proprietor of a boutique in New York wanted to determine the average age of his customers. A random sample of 25 customers revealed an average age of 28 years with a standard deviation of 10 years. Determine a 95% confidence interval estimate for the average age of all his customers. Assume the population of customer ages is normally distributed   23.872 to 32.128
128. The standard deviation for the lifetimes of washing machines is estimated to be 800 hours. What sample size must be selected in order to be 97% confident that the margin of error will not exceed 50 hours?  1206
129. Using α = .04, a confidence interval for a population proportion is determined to be .65 to .75. If the level of significance is decreased, the interval for the population proportion   becomes wider
130. We can use the normal distribution to make confidence interval estimates for the population proportion, p, when _____.  np ≥ 5 and n(1 − p) ≥ 5

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