. In a super marker the average arrival rate of customers is 5 in every 30 minutes. The arrival time it takes to list and calculate the customers purchase at the cash desk is 4.5min and this time is exponentially distributed(a) How long will the customer expect to wait for service at the cash desk?

3. In a super marker the average arrival rate of customers is 5 in every 30 minutes. The arrival time it takes to list and calculate the customers purchase at the cash desk is 4.5min and this time is exponentially distributed (a) How long will the customer expect to wait for service at the cash desk? [2] (b) What is the chance that the queue length will exceed 4? [51 (c) What is the probability that the cashier is working? [21