Question

A study of the career paths of hotel general managers sent questionnaires to an SRS of 193 hotels belonging to major U.S. hotel chains. There were 61 responses. The average time these 61 general managers had spent with their current company was 11.78 years. It is given that the standard deviation of time with the company for all general managers is 3.4 years. Calculate a 99.5% confidence interval for the mean number of years that general managers of major-chain hotels have spent with their current company.

A. 11.78 +/- 1.34

B. 11.78 +/- 1.12

C. 11.78 +/- 1.22

D. 11.78+/- .90

E. 11.78 +/- .81

F. 11.78 +/- .75

From the previous problem, suppose that we do not know that σ = 3.4, but the standard deviation of the sample is calculated to be 3.7. Calculate a 99.5% confidence interval for the mean number of years that managers have spent with their current company under the new conditions.

A. 11.78 +/- 1.26

B. 11.78 +/- 1.56

C. 11.78 +/- 1.47

D. 11.78 +/- 1.53

E. 11.78 +/- 1.38

F. 11.78 +/- 1.33

Answer 1

For Known

11.78+/- 1.22

for unknown

11.78+/- 1.38