Two students taking a chemistry class were doing well enough to think they had solid “A” grades. Confident of their chemistry knowledge, they decided to visit another college and party with some friends the weekend before the final. When they returned too late to take the exam, they found their professor and explained that they had missed the test because of a flat tire. The professor allowed them to make up the final the next day. When they arrived, the professor handed each a test, then placed them in separate rooms to begin. Opening the small booklets, the students found just one question: Which tire?