The following flow diagram depicts the operations of a call center. Calls arrive at the call center according to a Poisson process with rate l=20 calls per hour. A single Agent who spends, on average, two minutes per call, serves all arriving calls. This agent is able to fully handle 75% of the calls, while the remaining 25% of the calls need additional support and are served by a single Specialist who can serve 10 calls per hour. Assume both the Agent and the Specialist service times are exponentially distributed. a) (10 points) What is the average length of the queues (calls on hold) waiting for the Agent and for the Specialist? b) (5 points) What is the average time that a call spends in this call center? c) (5 points) What is the probability that an arriving call is put on hold? d) (5 points) All arriving calls use a toll-free (1-800) number, and so the call center pays for this service. The cost of a call is $0.1 per minute (during service and waiting). What is the cost (in $/hr ) that the call center is paying the phone company