A and B play a series of games. Each game is independently won by A with probability p and by B with probability 1−p. They stop when the total number of wins of one of the players is two greater than that of the other player.

The player with the greater number of total wins is declared the winner of the series.

(a) Find the probability that a total of 4 games are played.

(b) Find the probability that A is the winner of the series.