Problem:

You are planning a bank, You plan for six tellers. Tellers take 15 minutes per customer with a standard deviation of 7 minutes. Customers arrive one every three minutes according to an exponential distribution (recall that the standard deviation is equal to the mean). Every customer that arrives eventually gets serviced.

Required:

Question 1) On average, how many customers would be waiting in line?

Question 2) On average, how long would a customer spend in the bank?

Question 3) If a customer arrived, saw the line, and decided not to get in line, that customer has ________?

Question 4) A customer who enters the line but decides to leave the line before getting service is said to have _________?

Provide correct solution of the given problem with step by step calculations.