A customer arrives at an apple cider farm with a five-gallon container and asks the farmer to put four gallons of his finest cider into it. Unfortunately, the only measure the farmer has is a three-gallon jug. Can you think of a way that the farmer can measure out exactly four gallons of cider using just these two containers?
Answer
First, fill up the three-gallon jug. Pour the three gallons into the five-gallon container. Refill the three gallon jug and once again pour it into the five-gallon container until it is full. The three-gallon jug now contains one gallon. Empty the five-gallon container back into the storage tank and then pour the one gallon of cider into it. Now, fill the three-gallon jug up again and pour it into the customer’s five-gallon container. The container will now contain the desired four gallons.