Problem 3:

a. You have been observing the queue at a cafeteria and noticed that, on average, 5.5 students are in line at lunch each day and that students wait in the line for three minutes on average. What is the arrival rate (A) of students at the cafeteria? (5 points)

b. A grocery store has three open checkout lanes. On average, 45 shoppers arrive at these lanes per hour. The coefficient of variation of the interarrival time is equal to 1. The average service time for all the lanes is 18 customers per hour, and the coefficient of variation of the service time is equal to 3. If the customer waiting costs the grocery store owner 0.25 $/min. What is the total cost of waiting? (5 points)