17. The mean length of a work week for the population of workers was reported to be 39.2 hours (Investor’s Business Daily, September 11, 2000). Suppose that we would like to take a current sample of workers to see whether the mean length of a work week has changed from the previously reported 39.2 hours.

a. State the hypotheses that will help us determine whether a change occurred in the mean length of a work week.

b. Suppose a current sample of 112 workers provided a sample mean of 38.5 hours. Use a population standard deviation σ  4.8 hours. What is the p-value?

c. At α  .05, can the null hypothesis be rejected? What is your conclusion?

d. Repeat the preceding hypothesis test using the critical value approach.