A single teller serves the customers in a bank during the afternoon hours of 2 to 3 pm. The teller can serve a customer in an average of four minutes. Suppose that the arrival rates of customers are 10 customers per hour.
a. Find the operating characteristics of the single teller queuing system.
b. If the arrival rate of the customers goes up in the future, how high should the average arrival rate be before a second teller is added?