On Highland Island, there are two tribes of natives, the Chocolates and the Peaches. Chocolates always, always tell the truth to any question they are asked, and Peaches always, always lie. Members of the two tribes all look pretty much alike—that is, there is no way to tell who belongs to which tribe just by looking. Therefore, life is rather confusing on the island, as you are about to discover.
You have been taking a walk and are on your way back to your campsite. You have come to a fork in the trail, and it is getting dark, and you don’t know which way to go, and you are hungry. There is a native sitting by the side of the trail, eating a banana. He will answer exactly one question for you. Think up ONE QUESTION to ask this person so that you will learn which trail will take you to your campsite. (You may assume that the native knows which is the correct trail.) If you figure out the right question to ask, the native might be pleased enough to share his banana with you. Good luck!
There are several slick possibilities. You cannot just ask which trail leads back to your camp, because a Chocolate will point in the right direction and a Peach will point in the wrong direction, and you won�t know which is which. The trick is to get the native, not to answer the question, but to tell you what he would say in answer to a question. The Peach must lie about what he would say, so both a Chocolate and a Peach will say the same thing! So, how about this:
“If I ask you which trail will take me back to my camp, what will you say?”