The math prof makes a design inference ...

Four of the students in the math professor’s class were very smart young fellows, and they did not think they needed to study much.

Two days before the exam, they decided to go fishing. They had a good time, and got drunk in the local hotel on the last night. So on the morning of the exam they overslept.

They drove as fast as they could, but arrived back on campus after the exam was over.

What should they do? One of them had an idea. He went and told the professor: “We are awfully sorry we are late. We went away to a cottage to study. We had a flat tire on the way back.”

The professor summoned them all and said, “Sir, I am sorry to hear of your and your friends’ misfortune. Gentlemen, I will give you a chance to write the exam tomorrow morning at 9:00 a.m. In the meantime, I must insist that you all go to your own rooms and study separately. Do not communicate.”

The next morning, the professor put the young men in separate rooms. He handed out an exam that contained only two questions.

The first was a standard question they could all easily answer.

But when they turned over the page, they discovered that - for 50% of the mark - they had to answer the following question: Which tire?