Bank Teller) One teller has been serving all customers at a local bank branch in a small town of Boston. Customers arrive in a mean of 1/15 hours (or 4 minutes) with a standard deviation of 1/15 hours. The teller spends a mean of 1/20 hours (or 3 minutes) with a standard deviation of 1/20 hours. Customers visit the branch for different tasks, which creates the variability of service times. Some of their requests, such as money withdrawals, take a short time whereas others such as foreign money deposits take long. (Bank Teller) (a) Use the queueing template posted on Blackboard to calculate the average flow time (W). [Answer format: one decimal place] (b) Then use Little's law to calculate the average number of customers (L) either waiting in line or being served. [Answer format: integer] Write your answer(s) as 2.3, 4.