Turkish NMO First Round - 2000 P-35 (Combinatorics)
Source:
July 8, 2012
Problem Statement
If every k−element subset of S={1,2,…,32} contains three different elements a,b,c such that a divides b, and b divides c, k must be at least ?<spanclass=′latex−bold′>(A)</span>17<spanclass=′latex−bold′>(B)</span>24<spanclass=′latex−bold′>(C)</span>25<spanclass=′latex−bold′>(D)</span>29<spanclass=′latex−bold′>(E)</span>None