The Bank Manager of a Busy Downtown Location Found Herself

Multiple Choice

The bank manager of a busy downtown location found herself unable to find good teller help so she invested in an ATM to handle the routine withdrawals that tended to occupy an inordinate amount of the teller's time. Before she installed the ATM she found that customers were arriving on average every 2 minutes (Poisson distributed) and it took a teller 30 seconds (exponentially distributed) to process their request. The ATM is able to maintain a constant 30 second service time. What is the impact on the number of customers waiting in line?

A) There is no change.
B) The ATM line is half as long as the teller line.
C) The ATM line is twice as long as the teller line.
D) The ATM line is 25% shorter than the teller line.