[dread78645]

A hamburger was more likely to be 3 oz. than the 8-12 oz. ones we see today.

Less.

McDonalds used (and still uses) 10 burgers per pound of meat. Ray Kroc said that he wanted to simplify inventory; 100 buns = 10 lb = $15 in sales.
After Dave Thomas (Wendy's) introduced the 1/4 lb patty as the "standard", McD had to counter with it's Quarter-pounder®

[speekinout]

McDonalds used (and still uses) 10 burgers per pound of meat.

I believe that. And it seems like a reasonable portion to me. I haven't had many McD's, but their regular burger always seemed like enough. Esp. if one adds a side (not Super-Sized!)