Week of 10-4-98:

Timothy goes to a fountain which delivers an unlimited amount of water. He brings two empty containers, one capable of holding 7 liters, the other 11 liters.

How many operations does he need to fill one of the containers with exactly 6 liters?

Note: In each 'operation' one container must be completely filled or completely emptied.

Good Luck.

The answer is 10 operations.  They are as follows:

OPERATION:  Water in 7 L container (in L):Water in 11 L container (in L)

Fill 7 L container:  7:0

Pour contents of 7 L into 11 L container:  0:7

Fill 7 L container:  7:7

Pour contents of 7 L into 11 L container:  3:11

Empty 11 L container:  3:0

Pour 7 L container into 11 L container:  0:3

Fill 7 L container:  7:3

Pour 7 L container into 11 L container:  0:10

Fill 7 L container:  7:10

Fill 11 L container with  7 L container:  6:11

>>>There you have it.  The 7 L container now has 6 liters in it.