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Tue 21 Apr, 2009 05:21 pm
There is a prisoner who is about to be executed. The king decides to give him one last chance to live.
There are 2 doors, the life door and the death door. There is one guard standing by each door. Those 2 guards know which door is the life door and which is the death door. However, one of them always tells the truth and the other always tells a lie. There is no way you can identify which door is the life door or the death door. There is no way you can distinguish who is the one telling the truth.
The prisoner can only ask one guard one question. Then he needs to choose a door to walk in . If he walks in the death door, then he will be executed. If he walks in the life door, he can have a new life.
He did choose the life door and lived. What was the question he asked? How did he choose the door after he got the answer from one of the guards?
@ajettin,
One solution to this "classic" is
"Which door would the other guard tell me is for "life" ?
(...and take the other door...the logic is trivial)
However, I seem to remember there may be another solution.