UNIVERSITY BOOKSTORE – TEXTBOOK DEPARTMENT
Last semester, in the twelve 9 AM to 9 PM workdays of those two weeks, we served 21,600 customers.
10% of our early semester customers to buy one book, 20% to buy two, 25% to buy three, 30% to buy four, and 15% to buy five books.
The checkout counter had four electronic cash registers. The cashiers’ task included:
1. Keying into the register an inventory code number and a price for each book (Time required: 0.1 minutes per book);
2. Bagging books and receiving payment either by
a. collecting cash and making change (Time: 0.4 min per customer),
b. waiting while the customer wrote a check, then taking down the customer’s identification data (Time: 1.2 min per customer), or
c. running a credit card through the register’s automatic approval device, filling out a charge slip while waiting for an approval code, getting the customer’s signature, and returning the card (Time: 1.0 min per customer).
Store records indicated that about 40% of textbook customers paid cash, 40% paid by check, and 20% by credit card.
Demand during the first two weeks was fairly level, except during the first two days. The first two days were by far the busiest, with their total volume per day double the average daily volume of the twelve-day period. The busiest hours on those peak days were between noon and 4:00 PM, when students came to buy books just after attending their first classes. Customer arrivals during those peak hours ran at three times the average rate over the twelve days.