The management at BuyRite grocery stores wishes to estimate the amount of time that customers are spending, on average, in its stores and in a checkout line. The most obvious approach for determining this information is to simply record when a customer enters and exits the store. However, it is difficult to track the entering and exiting times of specific customers. We will look at the problem using an alternative approach. Over the past two weeks, the following data have been collected at BuyRite’s newest store during busy hours (this BuyRite is rather large and typically has 7 open checkout lines). For simplicity, let us assume that the overall capacity at checkout lines is higher than the arrival rate of customers into the store. Average rate of customers entering store = 305 customers/hour
Average number of customers in store = 146 customers
Percentage of customers who do not make a purchase = 5%
Average number of customers in the checkout lines = 24 customers
As their consultant, you have been asked by BuyRite’s management to address the following questions:
(a) How much time on average does a customer spend in the store?
(b) How much time on average does a customer spend waiting?