Hello, ballin_sensation!

The probability of Elena winning a game is . . . of losing,If the odds in favor of Boris beating Elena in a chess game are 5 to 4, what is the

probability that Elena will win an upset victory in a best-of-five chess tournament?

There are three ways in which she can win three games.

(1) She wins the first three games:

. . .

(2) She wins two of the first three games, then wins the fourth game.

. . .

(3) She wins two of the first four games, then wins the fifth game.

. . .

Therefore: .