14. Arrivals at the enquiry counter of Roshanara Transport Company are Poisson distributed with an average of six per hour. The time that the customers spend in seeking information from the clerk stationed at the counter is known to be exponentially distributed with an average of three minutes.

Using this information determine

(a) the probability that a customer reaching the counter shall have to wait for getting the needed information.

(b) the probability that a queue shall be formed.

(

c) the expected time that a customer shall wait in the queue to obtain information.

Suppose that the company manager employs another clerk if he is convinced that a customer has to wait for at least 4 minutes for receiving information. What arrival flow rate would justify employing the second clerk?