The Infamous Monty Hall Problem
You are presented with 3 doors (A, B, C) only one of which has something valuable to you behind it (the others are bogus) you do not know what is behind any of the doors
You choose a door
Monty then counters by
The question is
should you switch?
Another question is
Does it matter?
You should always switch. At this point in the game it is not a 50/50 chance between the two doors.
I found a website that describes it like this:
This is not an example of simple probability (suppose there are two doors, therefore there is a 1 in 2 chance of the car being behind either of the doors). This is an example of conditional probability: what is the chance of something happening, given that something else already has. The something else is that Monty will never open the door to the prize.