The mean length of the work week for the population of American workers was reported to be 39.2 hours with a standard deviation of 4.8 hours in September, 2000. A researcher wants to determine if the average work week has changed from 39.2 hours. A sample of 112 workers yielded a mean of 38.5 hours. Based on this sample, can we conclude at the 5% significance level that the average length of the work week has changed?

A.   State the null and alternate hypotheses

B.    Identify the test statistic

C.   State the decision rule.

D.   Show the appropriate calculations and state the statistical decision.

E.    What conclusions can you draw concerning the length of work week for the population of American workers?