Handshake Puzzle

Hasan and Lauren attended a dinner party with 4 other couples. Since some people already knew some of the other guests, every person at the dinner party shook hands with every person they had not met before. Lauren noticed that…

Logical List Puzzle

Which logical statement(s) below must be correct? Exactly one statement on this list is incorrect Exactly two statements on this list are incorrect Exactly three statements on this list are incorrect Exactly four statements on this list are incorrect Exactly…

Tennis Match Mystery

Abe, Ben, and Catelyn were playing 1-on-1 tennis matches one afternoon. After each match, the winner stayed on the court and the loser was replaced by the person who sat out. At the end of their session, Abe had played…

Same Place Same Time

You spend an entire day hiking up a mountain, and camp overnight at the top. The next day, you hike down the mountain along the same trail, starting around the same time you started the day before. How likely is…

Tale of Two Trains

There are two trains that run between two cities. The trains are identical and run on identical routes, so passengers have no preference between the two and would take whichever train that pulls into the station. The trains run at…

Moving Battleship Puzzle

You are trying to hit a moving battleship, but you have no way of monitoring its position. However, you have the following information: You know where the battleship started. You know when the battleship started moving. You know the battleship…

Simpson’s Paradox

Simpson’s Paradox (also sometimes known as the reversal paradox or Simpson’s reversal) refers to the phenomenon in which a trend or result that appears in multiple groups of data no longer appears—or in fact reverses—when the groups are combined.