Customers arrive at a bank that has 1 teller and they wait in line on a first-come, first-served basis. customers arrive according to a poisson process with a rate of 14.5 per hour. it takes on average 4 minutes for a customer to be served by the teller. no customer leaves without going through service with the teller. the standard deviation of the service time is 2 minutes. how long is the waiting line (in terms of number of people), on average? (enter a number to a single decimal place.)