This is the only information i have about this question! Please answer it

Question 2 A post office is considering whether to assign one or two postal clerks on-duty to keep open on Sunday, from 9 a.m. to 3p.m. Customers arrive at a rate of 8 per hour following a Poisson distribution and the service times for a customer is 4 minutes, exponentially distributed. The post office has a single queue for customers waiting for an idle postal clerk for service. Suppose the hourly rate of a postal clerk is $16.25, and it is estimated that a cost of $0.65 for each minute a customer spends waiting for service. (a) For the 1-clerk scenario, compute the probability that there are more than four customers in the post office. (b) For the 2-clerk scenario, compute the probability that no customer is in the post office. (c) By computing the total relevant cost per day for the two scenarios respectively, should the post office schedule 1 or 2 postal clerks on-duty on Sunday