13 Benny the Barber owns a one-chair shop. At barber college, they told Benny that his customers would exhibit a Poisson arrival distribution and that he would provide an exponential service distribution. His market survey data indicate that customers arrive at a rate of two per hour. It will take Benny an average of 20 minutes to give a haircut. 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 Benny's time.