Thanks Stump. I knew I got it wrong only when I saw the answer.

Fraggle, don't worry, I wasn't saying you should've got it. There are plenty of times I should've got things but my brain just let's me down at the last moment. I'll never forget getting 99% in a calculus test because I managed to add 7 and 6 together to get 15!! If you start looking in the wrong direction with something like that question, you might spend days trying to get the answer.

Do we know the problem below (which I'm not going to name because it'll be too easy for people to pull out the solution)? It's always a cracker to share with people.

**The "XXXXX XXXX" problem**

Imagine you're in a game. There are 3 doors in front of you which you cannot see behind. There is only you and the quiz host in this game.

Behind 2 doors are coconuts, and behind 1 door is a luxury yacht (they're big doors, ok?). Now, we'll assume you always want the luxury yacht, just in case there's anyone out there with a bizarre coconut fetish!

You are asked to pick a door.

The quiz host now removes one of the other doors (but he will never take away the luxury yacht because that'd be a pretty naff game).

You are then told you can either stick with the door you have chosen, or you can change to the other door. Remember, you still can't see what's behind either one.

**What should you do?**

Should you stick, change, or does it make naff all difference either way?

What are the probabilities each way?

NB - this is a question often used to show how straight forward logic can get the wrong answer and unpleasant, but well formulated maths will prevail, BUT if you are careful with your logic, you'll get it right.