A rural post office has one clerk servicing the office Deman

A rural post office has one clerk servicing the office. Demand is about 11 customers per hour during lunch hour (ca = 1) and the time it takes to serve a customer is about 5 minutes (cp = 1).

How many customers are waiting to be served (on average)?

9.74

8.45

10.08

11.00

Solution

Correct Answer:

C.10.08

Working note:

Mean number of customers arrived per hour () = 11

Time to service one customer = 5 minutes

So,

Mean number of customers served per hour (µ) = 60/5 = 12

No. of customers, waiting to be served = ^2/ (µ*( µ - )) = 11^2/(12*(12-11))

No. of customers, waiting to be served = 10.08