There are two containers. One holds exactly 7 quarts and the other holds exactly 9 quarts. There are

[math_celebrity]

There are two containers. One holds exactly 7 quarts and the other holds exactly 9 quarts. There are no markings on the containers that allow you to know when they contain one, two, three, four, five, six or eight quarts.

You have a tub full of water and you can fill and empty the 7 and 9 quart container however you wish. How can you end up with exactly 8 quarts in the 9 quart container?

1. Fill the 7-quart and pour it into the 9-quart
2. Fill the 7-quart and pour 2 quarts into the 9-quart. The 9-quart is filled and 5 quarts are remaining in the 7-quart
3. Empty the 9-quart
4. Pour the remaining 5 quarts that are in the 7-quart into the 9-quart
5. Fill the 7-quart and pour 4 quarts into the 9-quart, which will fill it. 3 quarts are remaining in the 7-quart
6. Empty the 9-quart
7. Pour the 3 quarts that are remaining in the 7-quart into the 9-quart container
8. Fill the 7-quart and pour 6 quarts into the 9-quart. This will fill it and leave 1 quart remaining in the 7-quart container
9. Empty the 9-quart
10. Pour the 1 quart from the 7-quart into the 9-quart
11. Fill the 7-quart and pour it into the 9-quart. There are now 8 quarts in the 9-quart container