Tracey baked a square cake whose surface is dissected
Source: AIMO 2008, TST 4, P2, Suggested by Christian Reiher
January 4, 2009
geometryrectanglecombinatorics unsolvedcombinatorics
Problem Statement
Tracey baked a square cake whose surface is dissected in a grid. In some of the fields she wants to put a strawberry such that for each four fields that compose a rectangle whose edges run in parallel to the edges of the cake boundary there is at least one strawberry. What is the minimum number of required strawberries?