Suppose a building has 5 floors (1–5), occupied by offices. The ground floor (0) is not used for business purposes. Each floor has 80 people working on it, and there are 4 elevators available. Each elevator can hold 10 people at one time.
The elevators take 3 seconds to travel between floors and average 22 seconds on each floor when someone enters and exits. If all of the people arrive at work at about the same time and enter the elevator on the ground floor, how should the elevators be used to get the people to their offices as quickly as possible?
Note: To make this problem more open-ended, allow students to decide how many people work on each floor, the times when people arrive in the morning, and how long the elevator takes to travel between floors, as well as how long it remains on each floor.