The mean and standard deviation of service times for customers at a post office are

known to be 2.93 minutes and 1.79 minutes, respectively.

(a) What is the probability that the average service time for the next two customers is

less than 2.7 minutes?

(c) What is the approximate probability that the total service time for the next 65

customers exceeds three hours? (Assume that the next 65 customers represent a

simple random sample and that there is always a customer waiting in line.)