At Purdue University, there were four students taking chemistry and all of them had an 'A' grade average. The four friends were so confident that the weekend before finals, they decided to go to Chicago, visit some friends and have a big party. They had a great time, but after all the partying, they slept all day Sunday and didn't make it back to the campus until too late Monday morning to take their tests. Since they missed the test, they decided they would explain to the professor why they were not there to take their tests. They told him they had visited friends but on the way back to W. Lafayette, they had a flat tire and found there was no spare in the car. As a result, they missed their finals. The Professor agreed they could make up the final the next day. The guys were excited and very much relieved. They all studied that night for their exams scheduled the following day. The next day the Professor placed them in separate rooms and gave them a test booklet. They each quickly answered the first problem which was worth 5 points. They all felt a sense of relief. With each of them in separate rooms, they thought this was going to be easy. Then they turned the page............................ On the second page was written; For 95 points, Which tire went flat?