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Gold on the island (Posted on 2003-05-29) Difficulty: 2 of 5
Timothy goes to the island of knights and liars searching for gold. On the way,he meets a native.

What one question could Timothy ask the native to find out if there is gold on the island?

See The Solution Submitted by Tim Axoy    
Rating: 3.5000 (6 votes)

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Some Thoughts re: Solution | Comment 2 of 15 |
(In reply to Solution by DJ)

Oops, I intended to elaborate before submitting that.

If the native is a liar, then if you asked if there were gold, his answer would be opposite of the truth. Then, if you asked if he had said 'yes,' his response would simply be the reverse of the first answer, and the response to the second question would be a truthful answer to "Is there gold on the island?"

If the native were a knight, then asking if there is any gold on the island will yield a truthful answer. Ask him, then, if he had just said yes, and his answer will be the same as the first one, again truthfully being an answer to "Is there gold on the island?"

So, if you ask "If I asked if there were gold on this island, would you say yes?" to either a knight or a liar, you will get the answer to whether or not there is gold or not.
  Posted by DJ on 2003-05-29 09:21:22

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