A host invites a friend over to play a game.
There are 3 doors. Behind 1 door is a car. Behind the other 2 doors are goats. The friend may choose one door. If the friend chooses the door with the car, they can keep it. If the friend chooses a door with a goat, they have to return the goat to the farm from whence it was borrowed. Goats go home. 10km