MathDB
Putnam 2006 B2

Source:

December 4, 2006
Putnaminequalitiespigeonhole principlecollege contests

Problem Statement

Prove that, for every set X={x1,x2,,xn}X=\{x_{1},x_{2},\dots,x_{n}\} of nn real numbers, there exists a non-empty subset SS of XX and an integer mm such that m+sSs1n+1\left|m+\sum_{s\in S}s\right|\le\frac1{n+1}