two subsets with no fewer than four common elements.
Source: All-Russian Olympiad 1996, Grade 9, First Day, Problem 4
April 18, 2013
probabilityexpected valuecombinatorics proposedcombinatoricsProbabilistic Methoddouble countingHi
Problem Statement
In the Duma there are 1600 delegates, who have formed 16000 committees of 80 persons each. Prove that one can find two committees having no fewer than four common members.A. Skopenkov