Benny owns a barber shop. His market survey data indicate that customers arrive at a rate of five per hour with a coefficient of variation of 0.5. It will take each barber an average of 20 minutes to give a haircut, with a standard deviation of 10. There are 3 barbers in the shop. Based on these figures, find the following:

a. The average number of customers waiting.

b. The average time a customer waits.

c. The average time a customer is in the shop.

d. The average utilization of a barbers time.