Four Quarts

If you had an infinite supply of water and a 5 quart and 3 quart jug, how would you measure exactly 4 quarts?

Solution

1. Fill the 5Q jug.
2. Pour contents of 5Q jug to fill the 3Q jug. This leaves 2 quarts in the 5Q jug.
   
3. Empty the 3Q jug.
4. Pour remaining 2 quarts from the 5Q jug into the 3Q jug. There is 1 quart of space left in the 3Q jug.
   
5. Fill the 5Q jug.
6. Pour water from the 5Q jug into the 3Q jug until it is full.
7. The 5Q jug now has 4 quarts.