A single ATM is located on the ground floor of a shopping center. Service time at this machine is exponentially distributed. On average, the ATM can serve a customer in 2 minutes. Customer arrivals at the machine are Poisson distributed, with an aver- age of 25 customers an hour.

a. What is the average amount of time required to get money from this ATM (in minutes)?

b. On average, how many people are waiting to use this ATM?

c. On average, how many customers could use this ATM in an hour?

d. What is the probability that the ATM is idle?

e. By how much would the wait for the ATM improve if new technology could reduce the average customer service time by 30 seconds?