How much ribs to feed a hundred people?

Figure that half a rack of baby back or St. Louis pork ribs per person is not enough, but a full rack is too much (well -- for some people). If you're using beef ribs, figure 3-4 large ribs per serving and you'll be safe. Id' go got 75 racks of baby backs, 60 racks of St. Louis. For beef, talk to the butcher -- I can't translate this into sides.