A tax consulting firm has three counters in its office to receive people who have problems concerning their income, wealth and sales taxes. On the average 48 persons arrive in an 8-hour day. Each tax adviser spends an average of 15 minutes on an arrival. If the arrivals are Poisson distributed and service times are exponentially distributed, find

 

a) average number of customers in the system, b) average number of customers waiting to be served, c) average time a customer spends in the system, d) average waiting time for a customer, e) the number of hours each week (5-working day) a tax adviser spends performing his job, ) the probability that a customer has to wait before he gets service, g) the expected number of idle tax advisers at any specified time.