Get a fox, a goose, and a sack of grain across the river without anyone eating lunch early. From the free puzzle set on Think Fanny — next try Three switches, one bulb.
The puzzle
A farmer needs to cross a river with a fox, a goose, and a sack of grain. The boat holds the farmer plus only one other thing.
If left alone together, the fox eats the goose, and the goose eats the grain. The fox will not eat the grain.
How does the farmer get everything across safely?
Answer
Take the goose first. Return alone. Take the fox (or grain). Bring the goose back. Take the grain (or fox). Return alone. Take the goose.
Never leave the fox alone with the goose, or the goose alone with the grain. The goose is the problem passenger, so it has to shuttle more than once.
