Post Office has a single line where customers wait for the first available window. There are four staffed with clerks capable of providing all services. A community group studying public services complained to the Postmaster that at lunchtime, the lines were too long and the service slow.
The Postmaster hired a summer intern to study the service. He found that on average 72 customers arrived per hour during lunch, while it took three minutes on average to serve each customer.
a) What is the average number of customers in line and what is the average time a customer spends in the post office? (Show all calculations)
b) The intern collected more data and found that 90% of customers required an average of only 2.5 minutes to be served but the remaining 10% had large packages to be sent parcel post and required an average of 7.5 minutes. With this information, the intern recommended that a separate line be established for parcel post with a dedicated window. The remaining thee windows would handle the other 90%, that is, all other business. Is this a good idea? (Show all calculations