Math Riddles

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.

Question: There are two ropes that both take exactly 1 hour to burn from end to end. You are unable to cut the rope. How can you burn the two ropes in a total of 45 minutes?

Question: Does a ton of feathers or a ton of bricks weigh more?

Question: Joe deals himself and his friend John some cards from a deck of cards (not the same amount). If John gives Joe some cards Joe will have 4 times as many cards as John. If Joe gives John the same number of cards he will have 3 times as many cards as John.

How many cards does each man have and how many cards do they trade?

Question: Mr. Smith has 4 daughters. Each of his daughters has a brother.

How many children does Mr. Smith have?