One day Bill complained to his friend that his elbow really hurt. His friend suggested that he go to a computer at the drug store that can diagnose anything quicker and cheaper than a doctor.

''Simply put in a sample of your urine and the computer will diagnose your problem and tell you what you can do about it. It only costs $10." Bill figured he had nothing to lose, so he filled a jar with a urine sample and went to the drug store. Finding the computer, he poured in the sample and deposited the $10. The computer started making some noise and various lights started flashing. After a brief pause out popped a small slip of paper on which was printed: "You have tennis elbow. Soak your arm in warm water. Avoid heavy lifting. It will be better in two weeks."

Later that evening while thinking how amazing this new technology was and how it would change medical science forever, he began to wonder if this machine could be fooled. He mixed together some tap water, a stool s