Short, Tricky Puzzles with Elegant Solutions

16.07.2018

Episode #7 of the course The world’s most compelling logic puzzles by John Robin

Welcome!

We’re back today for more logic puzzles. Are you all ready, with your coffee by your side? Time to fire up the mental engine!

Let’s look at two simpler problems. The beauty of logic puzzles is that even the short ones can be challenging, but their solution elegant once you get the trick behind them.

Puzzle 1. The Worker and the Gold Bar

You hire a worker and tell her she must work for you 7 days in a row. At the end of each day, if she completes her work, you’ll pay her 1/7 of a bar of gold. She requires 1/7 of a bar of gold every day to meet her basic needs. Your task is to make as few cuts to the gold bar as possible. How many cuts will you make to pay your worker 1/7 each day?

Enjoyed this puzzle? Let’s do another one.

Puzzle 2. The Jailer’s Dilemma

Four prisoners are arrested for a crime, but the jail is full, so the jailer has nowhere to put them. Eventually, he happens upon the following solution: Have them solve a puzzle. If they succeed, they can go free. If they fail, they will all be executed.

The jailer makes three of the now-nervous men sit so they form a row, one in front of the other. He makes the fourth sit in another room.

He gives all four men party hats. The jailer tells them there are two red and two blue hats. The prisoners can see the hats in front of them, but not their own, nor the hat on the one behind them. The fourth prisoner can’t see or be seen by any other prisoner.

The jailer says if any one of them can figure out and tell him what color hat he has on his head, then all four prisoners go free. How do they survive?

Work it out on your own first, then click the button below to find out if you’re right.

Tomorrow, we’ll increase the difficulty a bit with another one of my favorite puzzles. Enjoy your day!

Recommended book

My Best Mathematical and Logical Puzzles by Martin Gardner

Share with friends