Question: A farmer is trying to cross a river with a bag of corn, a hen, and a fox. The farmer's boat is only big enough to take himself and one other item per trip. The hen cannot be left alone with the corn or she will eat it. Likewise the fox cannot be left with the hen, or the hen will be eaten. How does the farmer get all three items across the river?
Answer: The farmer takes the hen across first, and leaves her on the other bank. Next, he comes back, loads the fox onto his boat, and takes him back across the river. He drops off the fox on the opposite bank, picks up the hen, and brings her back to the original bank. He swaps the hen for the corn, and returns to the far bank with the corn - leaving it with the fox. Then, he returns once more to the original bank to get the hen. Once he brings her across, all four are happy to be on the other side!