Most air travellers now use e-tickets. Electronic ticketing allows passengers to not worry about a paper ticket, and it costs the airline companies less than paper ticketing. However, recently 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 Watchcat agency contacted a random sample of 20 airports and collected information on the number of complaints the airport had with e-tickets for the month of March. The information is reported below.

14	14	16	12	12	14	13	16	15	14
12	15	15	14	13	13	12	13	10	13

At the .05 significance level, can the Watchdcat agency conclude the mean number of complaints per airport is less than 15 per month?

a. What assumption is necessary before conducting a test of hypothesis?

b. Plot the number of complaints per airport in a frequency distribution?

 Is it reasonable to conclude that the population follows a normal distribution?

c. Conduct a test of hypothesis and interpret the results. (cannot using p-value approach)