Unexpected Hanging Quiz Puzzle

This is a longstanding puzzle, first published in 1963 - we hope that you enjoy it.

A prisoner is sentenced to death by hanging, and to make the punishment more severe the hanging will be a surprise. The judge announces that the prisoner is to be hanged at noon on a weekday next week, and the prisoner will not know if he is to be executed that day until there is a knock on the cell door at midday, summoning him to the gallows.

The prisoner is delighted at this, reasoning as follows:

I can't be executed on a Friday, as if there has been no knock on the door by noon on Thursday the execution will not be a surprise.

Similarly I can't be executed on Thursday for the same reasons, as I know I can't be executed on Friday.

And by extension I can't be hanged on Monday, Tuesday or Wednesday either, so I'm free.

Then on Wednesday there is a knock on his door, which was a complete surprise to him, and he was hanged.

So where is the flaw in his reasoning?

As usual you can post your suggested answers as a comment on this website, reply to the post on Facebook, or retweet or reply on Twitter @quizmastershop.

Answer at 9.00 on Monday


  • There are no comments yet. Be the first one to post a comment on this article!

Leave a comment

Please note, comments must be approved before they are published