In a large university computing center, on average there are 10 service calls per day. A computer technician can handle on average 5 service calls per day. The cost of adding a technician (C1) is $200 per day and the estimated cost of waiting per incident (C2) is $250 per day. Find: (a) the optimum number if technicians needed in order to minimize the expected total cost, and (b) the average time a computer will remain down. (Avg time spent in the system)