On a small island, every resident either always tells the truth or always lies. You meet two residents, Leo and Mia. Leo says, 'At least one of us is a liar.' What are Leo and Mia?
Leo is a truth-teller and Mia is a liar.
If Leo were a liar, his statement that at least one of them is a liar would be true, creating a logical contradiction. Therefore, Leo must be a truth-teller. Since his statement is true, at least one of them must be a liar, which means Mia is the liar.
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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