Q2 (10 points) Consider a bank with a single line and 2 cashiers. Based on historical data, the manager knows that the average inter-arrival time (i.e., the time between two consecutive arrivals of customers) is 40 seconds and the standard deviation is 1 min. In addition, the manager knows that each cashier takes on average 2 minutes to process a request, with standard deviation 2 minutes.

(a) What is the average wait time of customers in the line? (2 points)

(b) What is the average time that a customer spends in the bank (either waiting or being

served)? (2 points)

(c) What is the average total number of customers that are inside the bank? (2 points)

(d) The manager is evaluating two options to improve the efficiency of the bank:

i. To train the cashiers to reduce the variability in their service, so that the standard deviation becomes 1 min.

ii. To train the cashiers to make them work faster, so that their average service time is 40 seconds.

Which option is more effective to reduce the average wait time in the queue? (3 points)