Turkish NMO First Round - 2012 Problem - 08 {Combinatorics}
Source:
July 1, 2012
algebrabinomial theorem
Problem Statement
In how many different ways can one select two distinct subsets of the set {1,2,3,4,5,6,7}, so that one includes the other?<spanclass=′latex−bold′>(A)</span>2059<spanclass=′latex−bold′>(B)</span>2124<spanclass=′latex−bold′>(C)</span>2187<spanclass=′latex−bold′>(D)</span>2315<spanclass=′latex−bold′>(E)</span>2316