An economist is back in his old college town many years after
graduation and decides to drop in on one of his old professors. He
happens to see a copy of an exam sitting on the desk, so he picks
it up to look at it. Upon deciding that it looks familiar, he comments
to the professor that it is the same exam that he had taken 10 years
ago. The professor assures him that this is correct, but adds that
this time the answers are different.