SCMA 350

Exhibit 8-2 The manager of a grocery store has selected a random sample of 100 customers. The average length of time it took these 100 customers to check out was 3.0 minutes. It is known that the standard deviation of the checkout time is 1 minute. 143. Refer to Exhibit 8-2. The standard error of the mean equals _____.

.1

Exhibit 8-2 The manager of a grocery store has selected a random sample of 100 customers. The average length of time it took these 100 customers to check out was 3.0 minutes. It is known that the standard deviation of the checkout time is 1 minute. 26. Refer to Exhibit 8-2. The standard error of the mean equals _____.

.1

Exhibit 8-1 In order to estimate the average time spent on the computer terminals per student at a local university, data were collected from a sample of 81 business students over a one-week period. Assume the population standard deviation is 1.2 hours. 140. Refer to Exhibit 8-1. The standard error of the mean is _____.

.133

Exhibit 8-1 In order to estimate the average time spent on the computer terminals per student at a local university, data were collected from a sample of 81 business students over a one-week period. Assume the population standard deviation is 1.2 hours. 23. Refer to Exhibit 8-1. The standard error of the mean is _____.

.133

Exhibit 8-2 The manager of a grocery store has selected a random sample of 100 customers. The average length of time it took these 100 customers to check out was 3.0 minutes. It is known that the standard deviation of the checkout time is 1 minute. 144. Refer to Exhibit 8-2. With a .95 probability, the sample mean will provide a margin of error of _____.

.196

Exhibit 8-2 The manager of a grocery store has selected a random sample of 100 customers. The average length of time it took these 100 customers to check out was 3.0 minutes. It is known that the standard deviation of the checkout time is 1 minute. 27. Refer to Exhibit 8-2. With a .95 probability, the sample mean will provide a margin of error of _____.

.196

Exhibit 8-1 In order to estimate the average time spent on the computer terminals per student at a local university, data were collected from a sample of 81 business students over a one-week period. Assume the population standard deviation is 1.2 hours. 141. Refer to Exhibit 8-1. With a .95 probability, the margin of error is approximately_____.

.26

Exhibit 8-1 In order to estimate the average time spent on the computer terminals per student at a local university, data were collected from a sample of 81 business students over a one-week period. Assume the population standard deviation is 1.2 hours. 24. Refer to Exhibit 8-1. With a .95 probability, the margin of error is approximately_____.

.26

124. 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 _____.

.50

180. 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

.50

63. Computing the necessary sample size for an interval estimate of a population proportion requires a planning value for P BAR (P with LINE OVER IT). 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

.50

7. 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 _____.

.50

134. If an interval estimate is said to be constructed at the 90% confidence level, the confidence coefficient would be _____.

.9

17. If an interval estimate is said to be constructed at the 90% confidence level, the confidence coefficient would be _____.

.9

135. If we want to provide a 95% confidence interval for the mean of a population, the confidence coefficient is _____.

.95

18. If we want to provide a 95% confidence interval for the mean of a population, the confidence coefficient is _____.

.95

11. The mean of the t distribution is _____.

0

128. The mean of the t distribution is _____.

0

Exhibit 8-3 A random sample of 81 automobiles traveling on a section of an interstate showed an average speed of 60 mph. The distribution of speeds of all cars on this section of highway is normally distributed, with a standard deviation of 13.5 mph. 148. Refer to Exhibit 8-3. The value to use for the standard error of the mean is _____.

1.5

Exhibit 8-3 A random sample of 81 automobiles traveling on a section of an interstate showed an average speed of 60 mph. The distribution of speeds of all cars on this section of highway is normally distributed, with a standard deviation of 13.5 mph. 31. Refer to Exhibit 8-3. The value to use for the standard error of the mean is _____.

1.5

Exhibit 8-3 A random sample of 81 automobiles traveling on a section of an interstate showed an average speed of 60 mph. The distribution of speeds of all cars on this section of highway is normally distributed, with a standard deviation of 13.5 mph. 147. 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

Exhibit 8-3 A random sample of 81 automobiles traveling on a section of an interstate showed an average speed of 60 mph. The distribution of speeds of all cars on this section of highway is normally distributed, with a standard deviation of 13.5 mph. 30. 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

169. 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

52. 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

125. We can reduce the margin of error in an interval estimate of p by doing any of the following EXCEPT _____.

124. 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 _____.

139. 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

22. 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

164. The t value with a 95% confidence and 24 degrees of freedom is _____.

2.064

47. The t value with a 95% confidence and 24 degrees of freedom is _____.

2.064

137. The z value for a 97.8% confidence interval estimation is _____.

2.29

20. The z value for a 97.8% confidence interval estimation is _____.

2.29

Exhibit 8-2 The manager of a grocery store has selected a random sample of 100 customers. The average length of time it took these 100 customers to check out was 3.0 minutes. It is known that the standard deviation of the checkout time is 1 minute. 146. Refer to Exhibit 8-2. The 95% confidence interval for the average checkout time for all customers is _____.

2.804 to 3.196

Exhibit 8-2 The manager of a grocery store has selected a random sample of 100 customers. The average length of time it took these 100 customers to check out was 3.0 minutes. It is known that the standard deviation of the checkout time is 1 minute. 29. Refer to Exhibit 8-2. The 95% confidence interval for the average checkout time for all customers is _____.

2.804 to 3.196

166. 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

49. 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

123. 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

6. 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

Exhibit 8-3 A random sample of 81 automobiles traveling on a section of an interstate showed an average speed of 60 mph. The distribution of speeds of all cars on this section of highway is normally distributed, with a standard deviation of 13.5 mph. 149. Refer to Exhibit 8-3. The 86.9% confidence interval for μ is _____.

57.735 to 62.265

Exhibit 8-3 A random sample of 81 automobiles traveling on a section of an interstate showed an average speed of 60 mph. The distribution of speeds of all cars on this section of highway is normally distributed, with a standard deviation of 13.5 mph. 32. Refer to Exhibit 8-3. The 86.9% confidence interval for μ is _____.

57.735 to 62.265

167. 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

50. 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

138. 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

21. 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

170. 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

53. 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

165. 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

48. 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

Exhibit 8-1 In order to estimate the average time spent on the computer terminals per student at a local university, data were collected from a sample of 81 business students over a one-week period. Assume the population standard deviation is 1.2 hours. 142. Refer to Exhibit 8-1. If the sample mean is 9 hours, then the 95% confidence interval is approximately _____.

8.74 to 9.26 hours

Exhibit 8-1 In order to estimate the average time spent on the computer terminals per student at a local university, data were collected from a sample of 81 business students over a one-week period. Assume the population standard deviation is 1.2 hours. 25. Refer to Exhibit 8-1. If the sample mean is 9 hours, then the 95% confidence interval is approximately _____.

8.74 to 9.26 hours

156. 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

39. 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

157. 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

40. 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

168. 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.

51. 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.

176. 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

59. 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

175. 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

58. 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

162. 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.

45. 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.

12. An interval estimate is used to estimate _____.

a population parameter

129. An interval estimate is used to estimate _____.

a population parameter

160. Whenever using the t distribution in interval estimation, we must assume that _____.

a random sample was selected

43. Whenever using the t distribution in interval estimation, we must assume that _____.

a random sample was selected

Exhibit 8-3 A random sample of 81 automobiles traveling on a section of an interstate showed an average speed of 60 mph. The distribution of speeds of all cars on this section of highway is normally distributed, with a standard deviation of 13.5 mph. 150. Refer to Exhibit 8-3. If the sample size was 25 (other factors remain unchanged), the interval for μ would _____.

become wider

Exhibit 8-3 A random sample of 81 automobiles traveling on a section of an interstate showed an average speed of 60 mph. The distribution of speeds of all cars on this section of highway is normally distributed, with a standard deviation of 13.5 mph. 33. Refer to Exhibit 8-3. If the sample size was 25 (other factors remain unchanged), the interval for μ would _____.

become wider

153. 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

36. 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

163. 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

46. 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

152. When the level of confidence increases, the confidence interval _____.

becomes wider

172. 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

35. When the level of confidence increases, the confidence interval _____.

becomes wider

55. 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

121. 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

4. 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

132. The confidence associated with an interval estimate is called the _____.

confidence level

133. The ability of an interval estimate to contain the value of the population parameter is described by the _____.

confidence level

15. The confidence associated with an interval estimate is called the _____.

confidence level

16. The ability of an interval estimate to contain the value of the population parameter is described by the _____.

confidence level

131. As the sample size increases, the margin of error _____.

decreases

14. As the sample size increases, the margin of error _____.

decreases

120. The t distribution is a family of similar probability distributions, with each individual distribution depending on a parameter known as the _____.

degrees of freedom

122. 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

3. The t distribution is a family of similar probability distributions, with each individual distribution depending on a parameter known as the _____.

degrees of freedom

5. 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

13. An estimate of a population parameter that provides an interval believed to contain the value of the parameter is known as the _____.

interval estimate

130. An estimate of a population parameter that provides an interval believed to contain the value of the parameter is known as the _____.

interval estimate

126. In determining an interval estimate of a population mean when σ is unknown, we use a t distribution with _____ degrees of freedom.

n − 1

9. In determining an interval estimate of a population mean when σ is unknown, we use a t distribution with _____ degrees of freedom.

n − 1

1. As the degrees of freedom increase, the t distribution approaches the _____ distribution.

normal

118. As the degrees of freedom increase, the t distribution approaches the _____ distribution.

normal

171. We can use the normal distribution to make confidence interval estimates for the population proportion, p, when _____.

np ≥ 5 and n(1 − p) ≥ 5

54. We can use the normal distribution to make confidence interval estimates for the population proportion, p, when _____.

np ≥ 5 and n(1 − p) ≥ 5

174. For which of the following values of p is the value of P(1 − p) maximized?

p = .50

57. For which of the following values of p is the value of P(1 − p) maximized?

p = .50

177. 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

60. 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

Exhibit 8-2 The manager of a grocery store has selected a random sample of 100 customers. The average length of time it took these 100 customers to check out was 3.0 minutes. It is known that the standard deviation of the checkout time is 1 minute. 145. Refer to Exhibit 8-2. If the confidence coefficient is reduced to .80, the standard error of the mean _____.

remains unchanged

Exhibit 8-2 The manager of a grocery store has selected a random sample of 100 customers. The average length of time it took these 100 customers to check out was 3.0 minutes. It is known that the standard deviation of the checkout time is 1 minute. 28. Refer to Exhibit 8-2. If the confidence coefficient is reduced to .80, the standard error of the mean _____.

remains unchanged

179. The margin of error in an interval estimate of the population mean is a function of all of the following EXCEPT _____.

sample mean

62. The margin of error in an interval estimate of the population mean is a function of all of the following EXCEPT _____.

sample mean

178. The degrees of freedom associated with a t distribution are a function of the _____.

sample size

61. The degrees of freedom associated with a t distribution are a function of the _____.

sample size

136. For the interval estimation of μ when σ is assumed known, the proper distribution to use is the_____.

standard normal distribution

19. For the interval estimation of μ when σ is assumed known, the proper distribution to use is the_____.

standard normal distribution

158. Whenever the population standard deviation is unknown, which distribution is used in developing an interval estimate for a population mean?

t distribution

41. Whenever the population standard deviation is unknown, which distribution is used in developing an interval estimate for a population mean?

t distribution

161. 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

44. 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

173. In determining the sample size necessary to estimate a population proportion, which of the following is NOT needed?

the mean of the population

56. In determining the sample size necessary to estimate a population proportion, which of the following is NOT needed?

the mean of the population

155. 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

38. 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

159. The t distribution should be used whenever _____.

the sample standard deviation is used to estimate the population standard deviation

42. The t distribution should be used whenever _____.

the sample standard deviation is used to estimate the population standard deviation

8. We can reduce the margin of error in an interval estimate of p by doing any of the following EXCEPT _____.

using a planning value p* closer to .5

10. The expression used to compute an interval estimate of μ may depend on any of the following factors EXCEPT _____.

whether there is sampling error

127. The expression used to compute an interval estimate of μ may depend on any of the following factors EXCEPT _____.

whether there is sampling error

151. In general, higher confidence levels provide _____.

wider confidence intervals

34. In general, higher confidence levels provide _____.

wider confidence intervals

154. 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

37. 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

2. If the margin of error in an interval estimate of μ is 4.6, the interval estimate equals _____.

x bar (x with line over it) +- 4.6

119. If the margin of error in an interval estimate of μ is 4.6, the interval estimate equals _____.

x bar +- 4.6 (x with line over it, +- on top of eachother)