Many Scuba Diving centers base their projections of revenues and profits on the assumption that the average Scuba diver dives five times per year. To disapprove the validity of this assumption, a random sample of 150 divers is drawn and each is asked to report the number of times he or she dived the previous year. The sample mean is 6.2 and let us assume that the population standard deviation is 4. Draw conclusion at 10% significance level. (Hint: this is a two-sided test.) Use the critical value approach.