The mean number of hours of flying time for pilots at Continental Airlines is 49 hours per month (The Wall Street Journal, February 25, 2003). Assume that this mean was based on actual flying times for a sample of 100 Continental pilots and that the sample standard deviation was 8.5 hours.

a. At 95% confidence, what is the margin of error?

b. What is the 95% confidence interval estimate of the population mean flying time for the pilots?

c. The mean number of hours of flying time for pilots at United Airlines is 36 hours per month (assume that this is just known to be true). Use your results from part b to discuss differences between the flying times for the pilots at the two airlines. The Wall Street Journal reported United Airlines as having the highest labor cost among all airlines. Does the information in this exercise provide insight as to why United Airlines might expect higher labor costs? Assume the salaries are the same for pilots at both airlines.