United Raiders Drive-In Market has one checkout counter where one employee operates the cash register. The combination of the cash resister and the operator is the server in this queuing system; the customers who line up at the counter to pay their selections form the waiting line. Customers arrive at a rate of 12 per hour according to a Poisson distribution, and service times are on average equal to 4 minutes per customer. What is the number of customers waiting in the queue on average