Question: You have a glass of water that looks about half full. How can you tell, only using the glass of water itself, if the glass is half full or not?
The glass is a right cylinder.
Answer: Tip the glass of water until the water reaches the rim of the glass and if the water lines up perfectly with the bottom rim of the glass, it is half full.
Question: A wise person was once sentenced to death by a king. The king couldn't decide how to execute him so he said to the wise person, you can say anything you want, if it is true, I will hang you, if it is not true I will shoot you. In the end the king released the wise man. What did the wise man say?
Answer: You will definitely shoot me.