My fave method--done this way for years . 6lb rib roast (I like the bone in)
Season w/salt, pepper, garlic powder (rub in well). Preheat oven to 375, cook roast uncovered for 1 hour.
Turn off oven (don't peek) and let set for 3 hours.
Turn oven back on (375) and cook about 45 minutes. Chk for internal temp of 140. Let rest 10 min before cutting. It has always been a success for me.