What was your question?

You leave your job interview in Liar and Truthteller Town with two other candidates who seem to know each other.
The interviewer has told you that one of them is a Liar and one is a Truthteller; but you were so nervous you didn’t ask him which was which. Out on the sidewalk the three of you find the local Witch selling apples from a booth. Wicked witches are notorious for making apples that will put you to sleep for one hundred years and you have a train to catch. But those apples look delicious. So you turn to the other candidates and randomly ask one for advice. Her answer tells you all you need to know about the local witch’s apples. What was your question?

Click here for the solution

Your question was: “Would the other person tell me that this apple is all right to eat?”

If the person is the Truthteller and the apple is fine, she will say, No, because that’s what the Liar would say. If the person
is the Liar and the apple is fine, she will say, No, because that’s not what the Truthteller would say.
Similarly, if the apple will put you to sleep, the person will have to say, Yes.

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