and apple juice. Rogers thought he must have had 10 cookies by now. Rogers decided to stay as long as the young man did, and he gauged that another 510 minutes at that station would be enough. As Rogers was about to leave, he approached the young athlete and said, "Excuse me, dude. Make sure you follow the recommendation and don't exercise today." To this, the athlete replied, "Thanks, old man." Rogers left, feeling old, stressed, and newly aware of his hypertension. He thought that maybe the donor flow in the blood clinic might need some improvement. After all, he had spent about one-and-a-half hours there. He also thought he could easily make some assumptions, use averages or modes when available, and simulate the mobile blood donor clinic to try out some new ideas. He thought that a person donating blood should not spend more than 45 minutes there and should not wait more than five minutes at each step in the system.