Most air travelers now use e-tickets. Electronic ticketing permits passengers to not worry about a paper ticket, and it costs the airline companies less to handle than paper ticketing. Though, in recent times, the airlines have received complaints from passengers regarding their e-tickets, particularly when connecting flights and a change of airlines were involved. To investigate the problem an independent watchdog agency contacted a random sample of 20 airports and collected information on the number of complaints the airport had with e-tickets during the month of March. The information is shown in the table below.

a.    Suppose that the data are approximately normally distributed, is there sufficient evidence for the watchdog agency to conclude that the mean number of complaints per airport is less than 15 per month? Use a .05 level of significance.

b.    Is the normality assumption in part a necessary? Explain your answer.

 c.    Using a graphical approach discussed in the course, determine whether or not the assumption of normality appears to be valid. Show your graph and explain your answer.