MathDB
Tennis

Source: Kürschák 2005, problem 2

July 13, 2014
probabilitycombinatorics unsolvedcombinatoricsProbability CombinatoricsProbabilistic Method

Problem Statement

A and B play tennis. The player to first win at least four points and at least two more than the other player wins. We know that A gets a point each time with probability p12p\le \frac12, independent of the game so far. Prove that the probability that A wins is at most 2p22p^2.