When n = 2, the ball reaches A1/2 *1/2 * =1/2, and reaches B and C 1/2 * 1/4.

When n = 3, the ball reaches A1/4 *1/2 * 2 =1/4, and reaches B and C 1/2 * 1/4 * 65438.

When n = 4, the ball reaches A at 3/8 * 1/2 * 2 = 3/8 and at1/4 *1/2+3/8 *12 = 5/1.

When n = 5, the ball reaches A at 5/16 *1/2 * 2 = 5/16, and at 3/8 *1/2+5//kloc-0 */kloc-0.

……

The probability that the ball reaches A is always the probability that the ball reaches B and C for the last time. With the increase of times, the probability of A, B and C holding the ball is getting closer and closer. That is, getting closer and closer to 1/3.