You are standing at a fork in the road, and you know that one path leads to your destination, while the other path leads to certain doom.
You also know that there are two people standing at the fork, one of whom always tells the truth and one of whom always lies.
You can only ask one question to one of the people to determine which path to take.
What question should you ask?
One possible solution to this puzzle is to ask either person the following question: “If I were to ask the other person which path leads to my destination, what would they say?”
If you ask the truthful person, they would honestly tell you what the liar would say, which would be the path to doom. If you ask the liar, they would lie about what the truthful person would say, which would also lead you to the path to doom.
Therefore, you should choose the opposite path to the one they indicate, and that will lead you to your destination.