Deck 14: Comparing Two Means

Question 1

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

Answer 1

Independent Groups Assumption

Question 2

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 ________________________ .

A)25.105
B)2.307
C)0.529
D)4.3589
E)None of the above.

Answer 2

0.529

Question 3

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 = post-workshop anxiety level - pre-workshop anxiety level, the correct alternative hypothesis to determine if this approach was successful is ________________________ .

A)µ_d = 0
B)µ_d < 0
C)µ_d > 0
D)µ_d ≠ 0
E)µ_d ≤ 0

Answer 3

µ_d < 0

Question 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.

Question 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.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.

Question 6

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

Question 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.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 pre- and post-workshop?

A)1.753
B)1.147
C)0.287
D)0.503
E)2.010

Question 8

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)H_0: µ₁ - µ₂ = 0 and H_A: µ₁ - µ₂ < 0.
B)H_0: µ₁ - µ₂ = 0 and H_A: µ₁ - µ₂ ≠ 0.
C)H_0: µ₁ - µ₂ = 0 and H_A: µ₁ - µ₂ > 0.
D)H_0: µ₁ - µ₂ > 0 and H_A: µ₁ - µ₂ < 0.
E)None of the above.

Question 9

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.

Question 10

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

Question 11

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

Question 12

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 t-test 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.

Question 13

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)µ_d = 0
B)µ_d < 0
C)µ_d > 0
D)µ_d ≠ 0
E)None of the above.