Last term, there were two students who were taking Chemistry and who did pretty well during the term on all of the assignments etc. Up to the final exam, they had consistently high marks.
These two friends were so confident going into the final that the weekend before exam week (even though the final was on Monday), they decided to go to a party with some friends. So they did this and had a great time. However, they ended up staying longer than they planned, and they didn't make it back to their university until early Monday morning.
Rather than taking the exam, they found their tutor afterwards and explained to him why they missed it. They told him that they went to their parents' for the weekend, and had planned to come back in time to study, but that they had a flat tyre on the way back and didn't have a spare and couldn't get help for a long time. So they were late getting back to campus.
The tutor thought this over and agreed that they could make up the exam. on the following day. The two students were elated and relieved. So, they studied that night and went in the next day at the time that their tutor had told them.
He placed them in separate rooms, handed each of them a test booklet and told them to begin. They looked at the first problem, which was something simple and was worth 5 points. "Cool" they thought, "this is going to be easy." They did that problem and then turned the page.
They were unprepared, however, for what they saw on the next page. It said: (95 points) "Which tyre?"