There is this exercise in the "Discreet Mathematics" book I'm reading for my computer science course, which is leaving me scratching my head.
This one question goes like this: "Each inhabitant of a remote village always tells the truth or always lies. A villager will only give a Yes or a No response to a question a tourist asks. Suppose you are a tourist visiting this area and come to a fork in the road. One branch leads to the ruins you want to visit, the other branch leads deeper into the jungle. A villager is standing at the fork in the road. What one question can you ask the villager to determine which branch to take?"
The answer is apparently: "If I were to ask you whether the right branch leads to the ruins, would you answer yes?"
I don't quite understand why this question would reveal the correct branch to you. Can someone clear that up for me?