The Veggie-Buffet Restaurant is a downtown expensive buffet-only restaurant that specializes in trendy vegetarian salads and soy-based meat substitutes. When customers first enter the restaurant, they immediately take a buffet tray and a large plate and pass though the buffet, selecting food items of their choice. The buffet is offered to all at a fixed price, and customers can eat as much as they can pile on their plate, but they cannot return to the buffet line once they have left it. At the end of the buffet line, customers are offered the option of purchasing non-fruit drinks or drinks in the fruit juice bar, which is located past the buffet line. Customers who pur¬chase the juice bar option are given a plastic glass that is tinted slightly blue. Those who do not purchase the juice bar option are given the same plastic glass but without the blue tint. The juice in the juice bar is made from fresh fruit and fresh fruit juice but mixed with a good bit of water and raw sugar.

Diluting the juice is necessary for cost-control rea¬sons; pure fresh juice would cost too much to offer. In any case, those with the blue-tinted glass are permitted to return as often as they want for refills. On the other hand, those with the clear plastic glasses are offered filtered water and ice in the same fruit bar area. Midge Greenwafer, the owner, has noticed in recent months that profits appear to be down even though the customer count seems to be holding steady. Her first reaction is look to the juice bar because the weekly bill for fresh fruits and juice is much higher than she would like it to be. She does not spend a lot of time in the restaurant because she has several other businesses, so she has to rely on restaurant employees to help her figure out the problem. So, Midge asked Sanahoria Hambre, her favorite shift manager, about what might be causing the problem.

Sanahoria had an immediate answer: "The problem is that many people are not paying for the juice bar but are filling their water glasses with juice. I see it all the time. Just yesterday, I saw a family of eight all freeloading on the juice bar." "That's theft," said Midge. "Yes, but there's not much we can do about it. We do not have the staff to constantly monitor the juice bar. Most of the time the problem just goes undetected. But when one of our staff does see a clear glass being used in the fruit bar, she politely reminds the customer that the juice bar is an extra charge." "Good," said Midge. "Now we just need a better way to detect customers doing this." a. Create a simple detection system that can be used to solve the juice bar crises. b. What do you think is the optimal role for detection in this problem?