You have a 3 gallon jug and a 5 gallon jug. You need to measure out exactly 7 gallons of water. How can you do?!
Answers:
Fill 5 gallon jug.
Pour out enough to fill 3 gallon jug
2 gallons remaining in 5 gallon jug.
Pour out contents of 3 gallon jug.
Pour remaining 2 gallons that are in the 5 gallon jug into 3 gallon jug.
Fill 5 gallon jug.
You now have a total of 7 gallons -- 2 in the 3 gallon jug and 5 in the 5 gallon jug!
Fill the 5 gallon jug. Pour from the 5 gallon into the 3 gallon to fill it. This leaves 2 gallons in the 5 gallon jug. Empty the 3 gallon jug. Pour the 2 gallons remaining in the 5 gallon jug into the 3 gallon jug. Fill the 5 gallon jug again. You now have 5 gallons in the 5 gallon jug and 2 gallons in the 3 gallon jug; 7 gallons total.
Good luck and enjoy.
