21. 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 woul provide an exponential service distribution. His market survey data indicate tha 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. 22. Bobby, another enterprising barber, is thinking about advertising in the local newspaper since he is idle 45 percent of the time. Currently, customers arrive, on average, every 40 minutes. What does the arrival rate need to be for Bobby to be busy 85 percent of the time