A warden offers three prisoners a chance at freedom. He shows them 3 red hats and 2 white hats. He blindfolds them, puts a hat on each, and hides the remaining two. Prisoner 1 (who sees P2 and P3) says 'I don't know my hat color.' Prisoner 2 (who sees P3) says 'I don't know my hat color.' Prisoner 3 (who is blindfolded and sees nobody) says 'I know my hat color!' What color is Prisoner 3's hat?
Red
P1 didn't see two white hats on P2 and P3 (otherwise P1 would know his hat is red). So at least one of P2/P3 has a red hat. If P3 had a white hat, P2 would realize his own hat must be red. Because P2 also didn't know, P3 deduced that his own hat must be red.
About this riddle
Logic riddles give you a few facts and ask what must be true. List what you know, cross out what cannot be, and see what is left.
Difficulty: Medium. More like this: Logic riddles with answers or try Einstein's Logic Grid for a different kind of puzzle.
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