Of course, how much a chick eats depends a great deal on its age. At about 8 weeks of age, a broiler chick is eating about 1/3 pound of feed each day.
From the table, a broiler by its 9th week will have eaten about 6,000 grams = 13.23 pounds.
Since you can process Cornish X broilers at just about any age, you can decide to do so at the time they have eaten all of their feed. If feed costs 35¢/pound at your feed store, you could decide that your 10 broilers will go into the freezer when they have eaten $50 in feed - as an example.