MathDB
IMO Shortlist 2011, Combinatorics 2

Source: IMO Shortlist 2011, Combinatorics 2

July 12, 2012
combinatoricsIMO ShortlistHi

Problem Statement

Suppose that 10001000 students are standing in a circle. Prove that there exists an integer kk with 100k300100 \leq k \leq 300 such that in this circle there exists a contiguous group of 2k2k students, for which the first half contains the same number of girls as the second half.
Proposed by Gerhard Wöginger, Austria