In the world series of baseball, two teams A & B play a sequence of games against each other and the first team that wins a total of four games become the winner of the world series. If the...

In the world series of baseball, two teams A & B play a sequence of games against each other and the first team that wins a total of four games become the winner of the world series. If the probability that team A will win any parties game against team B is 1/3, what's the probability that team A will win the world series?