Suppose we are interested in estimating the average number of customers in the supermarket. On average, there are 15 customers entering the supermarket every 5 minutes. And on average, a typical customer spends about 20 minutes in the supermarket (from entering to exiting the market).
a. Calculate the average number of customers in the supermarket.
b. About 20% of customers leave without making a purchase. On average, a customer spends about 5 minutes in the checkout area. Estimate the average number of customers in the checkout area.