How many cans of chili beans for 40?

I need more information to answer this question! To figure out how many cans of chili beans you need for 40 people, I need to know:

* How much chili beans does each person typically eat? Is it a small side dish, or the main part of the meal?

* What size are the cans of chili beans? Are they 15-ounce cans, or something else?