Calculating Meat Portions for Large Group

I couldn't find it in my cookbooks, but I have a cookbook from the National Cattlemen's Beef Association and if you Google them and find the website (not listed in the cookbook) I bet they either will have it there or will tell you if you e-mail them.

When more than one meat is offered, many people send a menu with the invitation so they will know how many want one meat and how many want the other. Then calculate how much you will need of each. I am sure there is a formula but when I cook for a lot, I think how much I would need for five people then multiply by the number I am having. If in doubt, ask the place where you are buying the meat.