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: There is a 5 gallon and a 3 gallon box. You also have a hose with unlimited water. How are you gonna make the 5 gallon have 4 gallons using your items? (You do not know the exact measure measurements of a gallon)
Answer: You fill the five gallon up and pour it into the 3 gallon. The dump the 3 gallon out and pour what was left in the 5 gallon into the 3 gallon so that you have 2 gallons in the 3 gallon. Then fill the 5 gallon up and pour it into the 3 gallon to fill it up. Now you have 4 gallons in the 5 gallons.