Skip to main content
OlympiadHQ

Browse · MathNet

Print

62nd Ukrainian National Mathematical Olympiad

Ukraine counting and probability

Problem

Given positive numbers. Consider all pairwise sums of these numbers. Show that there exist two sums that differ by no more than a factor of .
Solution
Let the numbers be arranged in non-increasing order: . Consider the sums . Therefore, some two of the sums differ by no more than a factor of .

Techniques

Pigeonhole principle