The Emperical Rule?
1) Normal Pink 2) Normal Standard Deviation Blue 3) RV Sigma Green I have been looking at the paper written long ago, entitled " Probably error of the Mean " by Student. He derives the Standard Deviation in full with all the proper Math. His formula can model any Distribution and in fact models both these two Distributions when n = 2 while adjusting " A " the constant and Sigma to model both distributions. My formula is only one of many that can be derived. I did have right that Tan-1 = Z.
I put all three distributions together