Twenty.
I would make 15 -16 pounds
On an average of 1/2 lb per person, you would need 100 lbs of brisket.
13lb = 5.897kg
6kg = 13lb 3.64oz
11stone 13lb is 75.75 kilograms.
1stone 13lb is 12.25 kilograms.
nobody knows for sure because it depends on how many pieces one person eats.But for an average person it would feed about 40 people. You usually count on 6oz per person cooked barbecue. And you can count on about 40-50% shrinkage during cooking if it is a Boston butt or brisket. Bill Barbecue Recipes - http://www.bbq-book.com
I would estimate about a half pound per person. In other words, quite a lot!
A blue whale can feed approximately feed 50,000 people
That will feed approximately 120 people.
1 bushel will feed 10 people