Questions that come for Olympiads and entrance examinations are of a different level. It would be better if PhysicsForums had a separate forum for Olympiads where one can discuss high level problems because such problem requires a great knowledge and good conceptual strength. Also such problems can be tackled easily with some guidance from good teachers. You may ask me to post it in the homework forums but schools will not give high level problems. And practising Olympiad level questions is normally not a part of the school curriculum.