ABSTRACT
A boy, a girl, and a dog are playing with a ball. The boy throws the ball to the girl 2/3 of the time and to the dog 1/3 of the time. The girl throws the ball to the boy 1/2 of the time and to the dog 1/2 of the time. The dog brings the ball to the girl all of the time. Then, on average, the boy will have the ball 3/13 of the time, the girl 6/13 of the time, and the dog 4/13 of the time.
