MathDB
Indian Team Selection Test 2010 ST3 P3

Source:

May 22, 2010
geometryrectangleinequalitiesalgebra unsolvedalgebra

Problem Statement

Let A=(ajk)A=(a_{jk}) be a 10×1010\times 10 array of positive real numbers such that the sum of numbers in row as well as in each column is 11. Show that there exists j<kj<k and l<ml<m such that ajlakm+ajmakl150a_{jl}a_{km}+a_{jm}a_{kl}\ge \frac{1}{50}