Riddle #15: River crossing
A farmer has a bag of corn, a hen, and a fox. He has to cross a river, but his boat is only big enough to carry one thing with him. If the hen is left with the corn, she will eat it. If the hen is left with the fox, the fox will eat the hen. How can the farmer get all the three things across the river?
The farmer takes the hen with him in the boat and leaves it on the other bank. He goes back and brings the fox back with him. He drops off the fox on the other side but then brings the hen back along with him. He then drops it on the first bank and takes the corn with him. He leaves the corn across the river with the fox. He then returns for the last time to get the hen.