Pa and David finally got me to see whatI hoped was supposed to be the question and appropraite answers. I'd like to clarify a couple things though. % grains per pound is the IBO minimum ( with a few minor adjustments. 6 Grains per pound is what most manufacturers state you must use to not violate warranty requirements. It's also true that they arrive at IBO rated speeds using nothing on the string and using 30" draw, 70#, and 350gr arrow. Now we have to consider that if you put things on the string (kisser, peep, string silencers, etc) that these things could be considered as part of the required weight needed to have that 6gr/lb. This means that your arrow does not necessarily have to weigh that much. Those other components are on the string and are there for every shot.
Also shorter draw persons and lower weights do not put as much stress on the bow or rigging and those persons can often times shoot a lighter arrow that "recommended" so as to gain some speed.