A man's car runs out of gasoline. His car tank holds exactly 13 gallons. He has three empty unmarked containers which can hold 3 gallons, 6 gallons, and 11 gallons. Using only these containers at the gas station, how can the man bring back exactly 13 gallons?

(He is not allowed to buy over 13 gallons and dispose of the extra.)

the man could fill the 11 container, then dump as much as possible into the 6 container, leaving him 5 in the 11. Then dump from 11 to 3. He now has 2 left in the 11. Return this amount to his car. bring the empty 11 back, dump both the 3 and 6 into the 11. Add more gasoline til the 11 is full. Return to his car again with the 11 and add it to the two in his tank allready. This gives him 13 gallons. It just gives the man a reason to have a fourth container. (Unless he left his car at home?)

Posted by Jon on 2003-04-11 12:45:11