answer all questions with explanation

6. Many best of seven series are scheduled so that the first two games are played at the home field of team A, the next three games are played at the home field of team B, and the last two are played back at the home field of team A. Of course, if one team wins 4 games before the series is over, then the remaining games will not be played. Assume that both reams win on their own home field with probability. (a) What is the probability that team A wins the series? (b) What is the expected number of games that the series goes to