1.23. A man takes a two-week cruise to Mexico from the U.S. Shortly after he gets back, he takes a three-day cruise which doesn't stop at any other ports. He stays in his cabin all the time on both cruises. As a result, he makes $250,000. (MI, from "The Wager")

1.23 answer: He's a smuggler. On the first cruise, someone brings the contraband to his cabin, and he hides it in an air conditioning duct. Returning to the U.S., he leaves without the contraband, and so passes through customs with no trouble. On the second trip, he has the same cabin on the same ship. Because it doesn't stop anywhere, he doesn't have to go through customs when he returns, so he gets the contraband off safely.