Question: how long does it take to cook a beef tenderloin at 350?
Answer: Preheat oven to 350 degrees F (175 degrees C). ... 
Place roast into a shallow, glass baking dish. ... 
Bake in preheated oven for 10 minutes, then turn the roast over, and continue cooking 35 to 40 minutes, basting occasionally until the internal temperature of the roast is at 140 degrees F (60 degrees C) for medium.