Generally plan on 4 to 6 oz. raw weight per serving so you would need 5 to 8 pounds of tenderloin. Pork tenderloins are generally 1  to 1 1/4 pounds each. Roast, uncovered, on a rack in a roasting pan (allow some space between them so you will need more than one pan) in a 425 degree oven for 30 to 40 minutes. Check doneness with an instant read thermometer inserted in the center of a tenderloin; it should register 155 degrees. Cover with foil and let stand 15 minutes; the temperature will rise 5 to 10 degrees (160 degrees final temperature).