there are 4 prisoners and they are about to get executed, but they are granted one last chance to survive...
They get lined up and are given hats, 2 white (X) and 2 black (O) hats. (the prisoners know there are two black and 2 white hats.)
they are lined up like this:
X O X | O
there are three prisoners in front of the wall and one behind ...they are all looking towards the Right -> and are not allowed to look back.they can only see the color of the hats in front of them.they are not allowed to communicate in any way.they do not know what color hat they themselves are wearing...they need to guess their hat color.if one of them guesses right, they all survive.if they guess wrong they all get executed ....they have 10min. time to decide...
How can they survive?