Two students decide to go skiing for the weekend, and are having such a good time they decide to blow off the exam that they have scheduled for Monday morning in order to get some final runs in before they head back to school. They decide to tell the professor that they got a flat tire and therefore deserve to take the exam at a rescheduled time.
Hearing the story, said professor agrees that it really was just bad luck, and of course they can take the exam later. At the appointed time, the professor greets them and places them in two separate rooms to take the exam.
The few questions on the first page are worth a minor 10% of the overall grade, and are quite easy. Each student grows progressively confident as they take the test, sure that they have gotten away with fooling the professor. However, when they turn to the second page they discover that they really haven’t.
The only question on the page, worth 90% of the exam, reads: "Which tire?"