FAQ

To answer your question, beef roasts can be done in a moderately slow oven (325 degrees) and need to be cooked 22-30 minutes per pound, depending on doneness.  So for example, a 10 pound beef roast to be done should be cooked approximately 4 hours 10 minutes (at 25 minutes per pound).  A 15-lb roast would take nearly 6.5 hours.  Covering with a lid or foil is helpful to retain moisture inside the pan and keep the roast moist and I would recommend this for such a large roast so the outside of the roast doesn't get too done and dry before the inside is cooked).  You don't have to add moisture when roasting, but pouring on some beef broth (use a bullion cube or spoonful of granules or a canned broth) over top of the roast and basting during the roasting process will increase it's tenderness and moistness when finished.  Again,in this case, I would recommend that you do this as the roast will be in the over for a long time (unless you cut it up into two smaller roasts  You should also use a meat thermometer to test doneness.  Beef roasts need to be done to 145 degrees F to be food-safe.  The only way to know for sure is to test using a meat thermometer.  See the link below for a thermometer chart on doneness (we also have these as fridge magnets available at our office for $0.10 each). 

http://www.fsis.usda.gov/PDF/IsItDoneYet_Magnet.pdf

You could also go to USDA's Is It Done Yet website for more information. http://www.fsis.usda.gov/is_it_done_yet/