Puzzle 119 - Prisoners with hats

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10 prisoners share a cell. The prison warden tells them that the next day they’ll be randomly lined up for execution. He’ll place either a black or white cap on everyone’s head. Each prisoner starting from the back of the line will guess what color his hat is. If he gets it wrong he’ll be executed. 

Every prisoner can not see the hat on his head or of those behind him. He can see the hats of everyone in front of him.  

How can the prisoners devise a strategy to save their lives? 

 

You can find the solution here. 

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