A software company operates a customer call center. Presently there are two support people who handle customer calls individually, and the average call takes 3 minutes to complete and follows exponential distribution. When both support people are busy, customers who call are placed in a queue. Calls arrive according to a Poisson process at a rate of 20 per hour.

(a) How large can the arrival rate become before the company will be forced to add another support person to keep up with the calls? (b) Modify your model to include the fact that customers will only wait, on av- erage, 5 minutes before reneging from the hold queue. Draw the state transition rate diagram and specify the birth and death rates for each state. You dont have to solve the model.