There is an advert running on UK television for Barclays Life Skills. A young lady is shown attempting to solve a puzzle, and then later shown fixing a problem with a wind turbine. The puzzle that she is solving is not shown in full, but if you know the puzzle you can infer what it is. Many of you will be unfamiliar with it, so being topical, we posed the puzzle last Friday, as follows.
A farmer is heading to market with a fox, a chicken and a bag of corn. No, we don’t know why he’s selling a fox, but it is needed for the puzzle. On his journey he reaches a river, which he has to cross using a small rowing boat. So small is the boat that it can only carry him and one of the items he’s taking to market at any one time. He needs to get the fox, the chicken and the bag of corn to market, so he has to get himself and the three items across the river somehow.
The problem he has is that the fox and the chicken are ravenously hungry, so if the fox is left with the chicken or the chicken left with the bag of corn, he will very quickly have only two items for sale. He has no means of keeping them apart while they are left.
How does he get the fox, the chicken, the corn and himself across the river without anything getting eaten?
The answer is to take the chicken across the river, leaving the fox with the bag of corn. He leaves the chicken on the far side and rows back across the river. Then he takes the fox across the river. Once he reaches the other side he drops off the fox and rows back across the river with the chicken. He then drops off the chicken on the original side and takes the bag of corn across the river. He leaves the fox and the bag of corn together and rows back to pick up the chicken, which completes the crossing.
You can reverse the order of the fox and the bag of corn for the same effect.