Refer to the previous exercise which asked for the distribution of the number of games played in a best of 5 series when team A wins with probability 50%.
a. Find the expected number of games played in a best of five series.
b. Find the expected number of games played when team A has an 80% chance of winning each game.

Previous exercise

Example 2 gave the probability distribution for the number of games played in a best out of seven series between teams A and B. Let’s derive the probability distribution for a best of five series, in which the team that gets 3 wins first wins the entire series.