MathDB
2012-2013 Winter OMO #12

Source:

January 16, 2013
Online Math Openanalytic geometry

Problem Statement

There are 25 ants on a number line; five at each of the coordinates 11, 22, 33, 44, and 55. Each minute, one ant moves from its current position to a position one unit away. What is the minimum number of minutes that must pass before it is possible for no two ants to be on the same coordinate?
Ray Li