The dog, the chicken and the grain
A farmer has to cross a river in a boat. He has a dog, a chicken and a bag of grain. He needs to get all 3 across safely but can only row one across at a time. If left alone, the dog will eat the chicken and the chicken will eat the grain. How does he do it?
Answer
The farmer takes the chicken to the far side and leaves it there. He returns in an empty boat and collects the dog. Travelling again to the far side he deposits the dog & picks up the chicken to return with it to the near side. At the near side he deposits the chicken and collects the grain. He rows the grain across to the far side and leaves the dog and grain together. He returns with an empty boat and collects the chicken. He rows to the far side with the chicken … and has all 3 across safely.