Question: You stand at a fork in the road. Next to each of the two forks, there stands a guard. You know the following things: First that one path leads to paradise, the other leads to Death. You cannot distinguish between the two paths. You also know that one of the two guards always tells the truth and the other always lies. You have permission to ask one guard one question to discover which path leads to paradise. What one question would you ask to guarantee you take the path to paradise?
Answer: Ask one of the gaurds 'Which door would the other guard say leads to paradise?' If you ask the truthful one he will say the lying guard would say the wrong door. If you ask the lying guard he would say the truthful gaurd would pick the wrong door as well (since he is lying). So no matter what you could choose the door opposite of what they say and end up in paradise.
Question: There is a farmer who has three sons. Nearing his death, he asked his three sons to find two objects that can fill the room he's in. The one who can deliver will be chosen as his heir. So the oldest son goes to the market to get hay while the middle son go get leaves. The youngest son goes to a shop and buys two things that he put in his pocket. The oldest son's hay only fills half the room, the middle son's leaves fills 2/4 quarters of the room, while the youngest fills the room with his two objects. Question: What are the two objects that the youngest son used to fill the room?
Answer: A match and a candle.