Three colored boxes are on a table: Red, Blue, and Green. One contains a coin, one contains a key, and one is completely empty. The label on the Red box says 'The coin is here.' The label on the Blue box says 'The Green box is empty.' The label on the Green box says 'The Red box contains the key.' If exactly one label is true, which box contains the coin?
The Red box
If Red is true, the coin is in Red, the key must be elsewhere, and Blue's claim ('Green is empty') is false, which fits the condition of exactly one true label.
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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