QA Chapter 13 (Test 3)

4. Data were collected on annual personal time (in hours) taken by a random sample of 16 women and 7 men employed by a medium sized company. The women took an average of 24.75 hours of personal time per year with a standard deviation of 2.84 hours. The men took an average of 21.89 hours of personal time per year with a standard deviation of 3.29 hours. The correct 90% confidence interval for the difference between women and men in the average number of hours of personal time taken per year is A. 0.30 to 5.48 hours. B. -0.50 to 3.21 hours. C. -4.67 to -0.62 hours. D. 1.27 to 6.89 hours. E. None of the above.

A. 0.30 to 5.48 hours.

2. A consumer group was interested in comparing the operating time of cordless toothbrushes manufactured by two different companies. Group members took a random sample of 18 toothbrushes from Company A and 15 from Company B. Each was charged overnight and the number of hours of use before needing to be recharged was recorded. Company A toothbrushes operated for an average of 119.7 hours with a standard deviation of 1.74 hours; Company B toothbrushes operated for an average of 120.6 hours with a standard deviation of 1.72 hours. Do these samples indicate that Company B toothbrushes operate more hours on average than Company A toothbrushes? The correct hypotheses to address this question are A. H0: μA - μB = 0 and HA: μA - μB < 0 B. H0: μA - μB = 0 and HA: μA - μB ≠ 0. C. H0: μA - μB = 0 and HA: μA - μB > 0. D. H0: μA - μB > 0 and HA: μA - μB < 0. E. None of the above.

A. H0: μA - μB = 0 and HA: μA - μB < 0

6T. A professor was interested in determining whether the prices of new textbooks in the bookstore were higher than if purchased online. She selected 6 textbooks and priced each at the bookstore and online. <b>DATA</b> Based on her analysis, we can conclude at the 0.05 level of significance that A. The prices are the same in the bookstore and online. B. The prices are higher in the bookstore. C. The prices are higher online. D. The prices are different in the bookstore and online. E. The analysis is not conclusive.

A. The prices are the same in the bookstore and online.

5. A consumer group was interested in comparing the operating time of cordless toothbrushes manufactured by two different companies. Group members took a random sample of 18 toothbrushes from Company A and 15 from Company B. Each was charged overnight and the number of hours of use before needing to be recharged was recorded. Company A toothbrushes operated for an average of 119.7 hours with a standard deviation of 1.74 hours; Company B toothbrushes operated for an average of 120.6 hours with a standard deviation of 1.72 hours. The 90% confidence interval is (-1.93, 0.13). The correct interpretation is A. We are 90% confident that, on average, there is no difference in operating hours between toothbrushes from Company A compared to those from Company B. B. We are 90% confident that, on average, the toothbrushes from Company A operate longer before needing to be recharged than the toothbrushes from Company B. C. We are 90% confident that, on average, the toothbrushes from Company B operate longer before needing to be recharged than the toothbrushes from Company A. D. We are 90% confident that, on average, there is a difference in operating hours between toothbrushes from Company A compared to those from Company B. E. None of the above.

A. We are 90% confident that, on average, there is no difference in operating hours between toothbrushes from Company A compared to those from Company B.

6. An army depot that overhauls ground mobile radar systems is interested in improving its processes. One problem involves troubleshooting a particular component that has a high failure rate after it has been repaired and reinstalled in the system. The shop floor supervisor believes that having standard work procedures in place will reduce the time required for troubleshooting this component. Time (in minutes) required troubleshooting this component without and with the standard work procedure is recorded for a sample of 19 employees. In order to determine if having a standard work procedure in place reduces troubleshooting time, they should use A. a one-tailed paired t-test. B. a two-tailed test of two independent means. C. a one-tailed test of two independent means. D. a two-tailed paired t-test. E. a test of two proportions.

A. a one-tailed paired t-test.

7. A mid-sized company has decided to implement an enterprise resource planning (ERP) system, and management suspects that many of its employees are concerned about the planned implementation. Managers are considering holding informational workshops to help decrease anxiety levels among employees. To determine whether such an approach would be effective, they randomly select 16 employees to participate in a pilot workshop. These employees were given a questionnaire to measure anxiety levels about ERP before and after participating in the workshop. To determine if anxiety levels about ERP decreases as a result of the workshop, they should use a A. one-tailed paired t-test. B. two-tailed test of two independent means. C. one-tailed test of two independent means. D. two-tailed paired t-test. E. one-tailed test of two proportions.

A. one-tailed paired t-test.

3. Results of a small experiment show that people are likely to offer a different amount for used exercise equipment when bargaining with a friend than when bargaining with a stranger. The p-value from testing the difference in mean offers was equal to 0.00162. At an α = 0.05, the correct conclusion is to A. reject the null hypothesis. B. fail to reject the null hypothesis. C. conclude that there is no difference between bargaining with a stranger versus a friend. D. Both A and C. E. Both B and C.

A. reject the null hypothesis.

6. Data were collected on annual personal time (in hours) taken by a random sample of 16 women and 20 men employed by a medium-sized company. The women took an average of 24.75 hours of personal time per year with a standard deviation of 2.84 hours. The men took an average of 20.5 hours of personal time per year with a standard deviation of 2.75 hours. If we use the pooled t-test to see if there is a difference between the two groups, the degrees of freedom for the appropriate t-statistic is A. 36 B. 34 C. 20 D. 16 E. None of the above.

B. 34

12T. Which of the following is not an assumption or condition that needs to be checked for a paired t-interval? A. Paired Data B. Independent Groups C. Randomization D. 10% Condition E. Nearly Normal Condition

B. Independent Groups

10. Which of the following is not an assumption and/or condition for the paired t-test? A. Nearly Normal Condition B. Independent Groups Assumption C. Paired Data Assumption D. Randomization Condition E. All of the above

B. Independent Groups Assumption

11T. A sample of 30 year fixed mortgage rates at 12 randomly chosen credit unions yields a mean rate of 6.65 % and a sample standard deviation of 0.38%. A sample of 30 year fixed mortgage rates at 16 randomly selected banks yields a mean rate of 7.05% and a sample standard deviation of 0.22%. Are the mean rates different between credit unions and banks? Relevant output is shown below. Which of the following is true? <b>DATA</b> A. This is a paired design. B. This is a test of two means from independent samples. C. This is a one tailed test. D. Both A and C. E. Both B and C.

B. This is a test of two means from independent samples.

1. A consumer group was interested in comparing the operating time of cordless toothbrushes manufactured by two different companies. Group members took a random sample of 18 toothbrushes from Company A and 15 from Company B. Each was charged overnight and the number of hours of use before needing to be recharged was recorded. Company A toothbrushes operated for an average of 119.7 hours with a standard deviation of 1.74 hours; Company B toothbrushes operated for an average of 120.6 hours with a standard deviation of 1.72 hours. The t-test for two means is appropriate in this situation because A. the two companies are dependent. B. the two companies are independent. C. the two companies are matched samples. D. the observations are paired. E. None of the above.

B. the two companies are independent.

1*. Data were collected on annual personal time (in hours) taken by a random sample of 16 women and 7 men employed by a medium sized company. The women took an average of 24.75 hours of personal time per year with a standard deviation of 2.84 hours. The men took an average of 21.89 hours of personal time per year with a standard deviation of 3.29 hours. The Human Resources Department believes that women tend to take more personal time than men because they tend to be the primary child care givers in the family. The ttest for two means is appropriate in this situation because A. women and men are dependent samples. B. women and men are independent samples. C. women and men are matched samples. D. the observations are paired. E. None of the above.

B. women and men are independent samples.

8. A mid-sized company has decided to implement an enterprise resource planning (ERP) system, and management suspects that many of its employees are concerned about the planned implementation. Managers are considering holding informational workshops to help decrease anxiety levels among employees. They randomly select 16 employees to participate in a pilot workshop. These employees were given a questionnaire to measure anxiety levels about ERP before and after participating in the workshop. If we let d = postworkshop anxiety level - pre-workshop anxiety level, the correct alternative hypothesis to determine if this approach was successful is A. μd = 0 B. μd < 0 C. μd > 0 D. μd ≠ 0 E. μd ≤ 0

B. μd < 0

7. An army depot that overhauls ground mobile radar systems is interested in improving its processes. One problem involves troubleshooting a particular component that has a high failure rate after it has been repaired and reinstalled in the system. The shop floor supervisor believes that having standard work procedures in place will reduce the time required for troubleshooting this component. Time (in minutes) required troubleshooting this component without and with the standard work procedure is recorded for a sample of 19 employees. The standard error of the mean difference is <b>CHART<b> A. 25.105 B. 2.307 C. 0.529 D. 4.3589 E. None of the above.

C. 0.529

5. Data were collected on annual personal time (in hours) taken by a random sample of 16 women and 20 men employed by a medium-sized company. The women took an average of 24.75 hours of personal time per year with a standard deviation of 2.84 hours. The men took an average of 20.5 hours of personal time per year with a standard deviation of 2.75 hours. The pooled estimate of the variance is A. 264.6715 B. 2.790 C. 7.785 D. 12.998 E. None of the above.

C. 7.785

2. Data were collected on annual personal time (in hours) taken by a random sample of 16 women (group1) and 7 men (group 2) employed by a medium sized company. The women took an average of 24.75 hours of personal time per year with a standard deviation of 2.84 hours. The men took an average of 21.89 hours of personal time per year with a standard deviation of 3.29 hours. The Human Resources Department believes that women tend to take more personal time than men because they tend to be the primary child care givers in the family. The correct null and alternative hypotheses to test this belief are A. H0: μ1 - μ2 = 0 and HA: μ1 - μ2 < 0. B. H0: μ1 - μ2 = 0 and HA: μ1 - μ2 ≠ 0. C. H0: μ1 - μ2 = 0 and HA: μ1 - μ2 > 0. D. H0: μ1 - μ2 > 0 and HA: μ1 - μ2 < 0. E. None of the above.

C. H0: μ1 - μ2 = 0 and HA: μ1 - μ2 > 0.

19T. An urban planning group is interested in estimating the difference in mean household income between two neighborhoods. They obtain the following 95% confidence interval: 95% CI for difference: (-5693, -4107). Which of the following is true? A. This is a paired design. B. There is no significant difference in the mean household incomes between the two neighborhoods at α = 0.05. C. There is a significant difference in the mean household incomes between the two neighborhoods at α = 0.05. D. Both A and B. E. Both A and C.

C. There is a significant difference in the mean household incomes between the two neighborhoods at α = 0.05.

8*. An army depot that overhauls ground mobile radar systems is interested in improving its processes. One problem involves troubleshooting a particular component that has a high failure rate after it has been repaired and reinstalled in the system. The shop floor supervisor believes that having standard work procedures in place will reduce the time required for troubleshooting this component. Time (in minutes) required troubleshooting this component without and with the standard work procedure is recorded for a sample of 19 employees. Assuming that we define our differences as Time without standard work procedure - Time with standard work procedure, the correct alternative hypothesis is A. μd = 0. B. μd < 0. C. μd > 0. D. μd ≠ 0. E. None of the above.

C. μd > 0.

10. A mid-sized company has decided to implement an enterprise resource planning (ERP) system, and management suspects that many of its employees are concerned about the planned implementation. Managers are considering holding informational workshops to help decrease anxiety levels among employees. They randomly select 16 employees to participate in a pilot workshop. These employees were given a questionnaire to measure anxiety levels about ERP before and after participating in the workshop. At the 90% confidence level, what is the margin of error for the mean difference in anxiety levels preand post-workshop? <b>CHART</b> A. 1.753 B. 1.147 C. 0.287 D. 0.503 E. 2.010

D. 0.503

3. Data were collected on annual personal time (in hours) taken by a random sample of 16 women and 7 men employed by a medium sized company. The women took an average of 24.75 hours of personal time per year with a standard deviation of 2.84 hours. The men took an average of 21.89 hours of personal time per year with a standard deviation of 3.29 hours. The standard error of the sampling distribution for the difference between the two means is A. 2.05 B. 5.02 C. 2.24 D. 1.43 E. 0.48

D. 1.43

4. Data were collected on annual personal time (in hours) taken by a random sample of 16 women (group1) and 7 men (group 2) employed by a medium sized company. The women took an average of 24.75 hours of personal time per year with a standard deviation of 2.84 hours. The men took an average of 21.89 hours of personal time per year with a standard deviation of 3.29 hours. The Human Resources Department believes that women tend to take more personal time than men because they tend to be the primary child care givers in the family. The results of the test are t = 2.02 with an associated P-value of 0.0352. The correct conclusion at α = 0.05 is to A. reject the null hypothesis. B. fail to reject the null hypothesis. C. conclude that women take a higher average number of hours of personal time per year compared to men. D. Both A and C. E. Both B and C.

D. Both A and C.

4T. A sample of 30 year fixed mortgage rates at 12 randomly chosen credit unions yields a mean rate of 6.65 % and a sample standard deviation of 0.38%. A sample of 30 year fixed mortgage rates at 16 randomly selected banks yields a mean rate of 7.05% and a sample standard deviation of 0.22%. Are the mean rates different between credit unions and banks? Relevant output is shown below. At the 0.05 level of significance, the correct conclusion is <b>DATA</b> A. Reject the null hypothesis. B. Do not reject the null hypothesis. C. Evidence suggests that there is a significant difference in mean mortgage rates between credit unions and banks. D. Both A and C. E. Both B and C.

D. Both A and C.

9*. An army depot that overhauls ground mobile radar systems is interested in improving its processes. One problem involves troubleshooting a particular component that has a high failure rate after it has been repaired and reinstalled in the system. The shop floor supervisor believes that having standard work procedures in place will reduce the time required for troubleshooting this component. Time (in minutes) required troubleshooting this component without and with the standard work procedure is recorded for a sample of 19 employees. The P-value associated with the calculated test statistic is < 0.001. At α = 0.05, the correct conclusion is to A. reject the null hypothesis. B. fail to reject the null hypothesis. C. conclude that having standard work procedures in place reduces troubleshooting time for this component. D. Both A and C. E. Both B and C.

D. Both A and C.

9. Managers are considering holding informational workshops to help decrease anxiety levels among employees. They randomly select 20 employees to participate in a pilot workshop. These employees were given a questionnaire to measure anxiety levels before and after participating in the workshop. A test was performed to determine if the workshop was successful in decreasing anxiety levels. The test results yielded a P-value of 0.008. The correct conclusion at α = .05 is A. to accept the null hypothesis. B. to reject the null hypothesis. C. to conclude that participating in the workshop decreases employee anxiety about ERP. D. both A and C. E. both B and C.

E. both B and C.