A study of the multiple-channel food-service operation at the Red Birds baseball park shows that the average time between the arrival of a customer at the food-service counter and his or her departure with a filled order is 10 minutes. During the game, customers arrive at the rate of four per minute. The food-service operation requires an average of 2 minutes per customer order. a. What is the service rate per channel in terms of customers per minute? b. What is the average waiting time in the line prior to placing an order? c. On average, how many customers are in the food-service system?