Thanks a lot everyone. Well ExEng.. you were unable to answer the question with your primary school education, or whatever level you managed to reach. Also, it had nothing to do with flying of the aircraft.
Either way, I was already aware of the formula, phiggsbroadband did mention. I didn't mean to be rude to him/her. But the answers are close, but not exact.
I am looking for the method the authorities/Jeppesen use to determine these values. The only thing, that makes sense, is they add some kind of a margin for obstacle clearance, depending on the runway, for which the approach is designed or as reynoldsno1 mentioned, different methodologies in place.