MathDB
2004 Combinatorics #5

Source:

December 30, 2011
probability

Problem Statement

A best-of-9 series is to be played between two teams; that is, the first team to win 5 games is the winner. The Mathletes have a chance of 23\tfrac{2}{3} of winning any given game. What is the probability that exactly 7 games will need to be played to determine a winner?