JEE Main 2026 Mathematics question
Two players A and B play a series of games of badminton. The player, who wins 5 games first, wins the series. Assuming that no game ends in a draw, the number of ways, in which player A wins the series is .
Answer: 126
Solution
A wins the series by winning game k (k=5 to 9) having won exactly 4 of the previous k−1 games: Σ_{k=5}^{9}C(k−1,4) = 1+5+15+35+70 = 126.