I hope you are purposefully trying to be obtuse. The alternative is rather disturbing.
I think the confusion is on the fat...well there is ground fat, and there is fat that is marbled in the meat naturally. The meat company does have a way of making the hamburger that gives you the 70/30 ratio. Not the same as the ribeye marbled steak.
http://firstwefeast.com/eat/guide-to-burger-blends-with-tom-mylan/
By playing the fool, a lot of information about the subject has been put forward by many posters, thus enlightening everybody, especially those who might have similar questions, but don't want to ask.
That being said, if you buy a package of 'hamburger' at the store, and it says 70% lean / 30%fat, how much fat is in it, exactly ?
IF it says 80% lean / 20%fat, then how much ?
Have you ever taken hamburger you purchased and verified these figures for yourself ?
The real difference (I am told) is in how much it shrinks during cooking, and how much grease(fat) it produces(separates) via cooking.