Three colored boxes—Red, Blue, and Green—stand in a row. Exactly one box contains a key. The Red Box says: 'The key is in the Blue Box.' The Blue Box says: 'The key is not in this box.' The Green Box says: 'The key is not in the Red Box.' If only ONE statement is true, which box contains the key?
The Red Box
If the key is in Red: Red's claim is False, Blue's claim is True, and Green's claim is False. This leaves exactly 1 true statement. If the key were in Blue or Green, 2 statements would be true.
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: Hard. More like this: Logic riddles with answers or try Einstein's Logic Grid for a different kind of puzzle.
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