Four people stand single-file facing a wall: Person 1 sees Persons 2 and 3; Person 2 sees Person 3; Person 3 sees only the wall; Person 4 is behind a solid barrier and sees no one. They know there are 2 black hats and 2 white hats among them. Person 1 says, 'I do not know my hat color.' Upon hearing this, Person 2 immediately states their own hat color correctly. How did Person 2 know?
Person 2 realized Person 1 would only know their hat color if Persons 2 and 3 wore matching hats. Since Person 1 did not know, Person 2 deduced that Person 2 and Person 3 must wear different colors. Person 2 looked at Person 3's hat and knew their own was the opposite.
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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