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.)

• you just fill up the 11 gallons and pour in some into the 3 gallons
• you have 8 gallons in the 11 gallon container
• then you fill up 5 gallons of the 6 gallons
• so you have exactly 13 gallons

Posted by Robert Hunter on 2004-09-29 12:29:17