This week we have quite a famous puzzle, but one that's worth sharing if you've not seen it. And it's an interesting and counter intuitive puzzle as well!
It first came to prominence in 1990 as a reader's question to Marilyn vos Savant's column in Parade magazine:
This is loosely based on an actual game show where this was the problem given to contestants.
So, you are on the game show you are asked to pick a door. You do so and the host opens one of the other two doors to reveal a goat. You can stick with your original door or change to the other unopened door. Do you stick? Do you change? Or does it make no difference?
As usual you can post the 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