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 60 seconds (Poisson distributed) and it took a teller 20 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 waiting time for the customers?

A) There is no change.
B) The wait in the ATM line is 50% shorter than the wait in the teller line.
C) The wait in the ATM line is 50% higher than the wait in the teller line.
D) The wait in the ATM line is 25% shorter than the teller line.