9. Customers for a local bakery arrive randomly following a Poisson process. The single salesman can attend customers at an average rate of 12 customers per hour, the service time being distributed exponentially. The mean arrival rate of the customers is 20 per hour.

Is the above queuing system workable? If not, why? If yes, determine the following:

(a) the mean number of customers in the bakery.

(b) the mean time spent by a customer in the bakery.

(

c) the expected number of customers waiting to be served.

(

d) the mean waiting time of a typical customer in the queue.