you are walking through a forest.when you come across 2 paths 1 which will lead you out of the forest, 1 which you will get complitely lost, they are 2 twins who know which path you should take, but 1 twin always lies & 1 always tells the truth, you can only ask 1 question, which question should you ask
You ask one of them what the other would say, then do the opposite. eg "Which path would the other twin tell me to choose?" When he tells you, take the other path.
ASK ONE OF THEM " IF I ASKED YOUR TWIN WHICH PATH TO TAKE, WHAT WOULD THEIR ANSWER BE?"...........WHATEVER ANSWER YOU ARE GIVEN, YOU TAKE THE OPPOSITE!
Or alternatively, you could ask no questions and say 'follow me': If you take the wrong route they're hardly going to follow you so you can double-back and take the correct one. Then you can tell them to go and get lost!