MathDB

no of unequal subsets of X={1,2,3,...,12} so that A\cap B={2,3,5,7,8}

Source: CRMO 2012 Region 2 p4

September 30, 2018

SubsetscombinatoricsCombinatorics of set

Problem Statement

Let

X=\{1,2,3,...,12\}

. Find the number of pairs of

\{A,B\}

such that

A\subseteq X, B\subseteq X, A\ne B

and

A\cap B=\{2,3,5,7,8\}