Assignment:
The manager of the Safeway store (close to Santa Clara University) is considering improving the customer service level by reducing customers' average waiting time for checkout. Based on the past year's data, he knows that customers try to check out every 2 minutes, on average, and the standard deviation of the interarrival time is also 2 minutes. It takes on average 3 minutes to finish the checkout process. The standard deviation of the processing times is 3 minutes. The manager's goal is to make sure the customers' average waiting time is less than 0.5 minute. How many checkout cashiers should the manager use?