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 cannot dispose of any extra gas, but perhaps he can find or borrow another container at the gas station to hold some gas for a minute. If so, he can top off the 11-gallon container, then use it to fill the 6 and 3. He can then pour the remaining 2 gallons into the spare container, pour the 6 and 3 into the 11, top it off, pour the 2 gallons back into the 6 or 3, and go back to his car.

Posted by Bryan on 2003-04-11 11:55:16