During a busy hour, the number of calls per hour for each of the 12 cells of a cellular cluster is 2220, 1900, 4000, 1100, 1000, 1200, 1800, 2100,...

During a busy hour, the number of calls per hour for each of the 12 cells of a cellular cluster is2220, 1900, 4000, 1100, 1000, 1200, 1800, 2100, 2000, 1580, 1800 and 900. Assume that 75%of the car phones in this cluster are used during this period and that one call is made perphone.a) Find the number of customers in the system