For perfectly tender roast beef, you'll need to plan on about 22-25 minutes per pound for a well-done roast, 17-19 minutes for medium, and 13-15 minutes per pound for rare. Since oven temps can vary, you can always check the roast to ensure it reached the appropriate internal temperature: 160℉/72℃ for a medium roast and 145℉/63℃ for a medium-rare roast. Since this chunk of meat is quite large, it will continue cooking after you take it out of the oven as it rests, so you may want to take it out when it's about 5℉/15℃ below the desired temperature.