Logic Puzzles

The odds of your first choice are 1/3. When one of the three is removed, the odds change to 1/2 - but only for the door you haven't chosen. That is, the door you're on remains 1/3 as it was so when you chose it, and it was not taken into consideration when the other door was removed.

So you can move from a 1/3 chance to a 1/2 chance by switching.

(It's called the Monty Hall Problem if you do want to read up on it).

Can of worms. Cheers though. I'm content just knowing I can put a name to it.