When cooking a ham roast you should cook the ham roast for 15 to 20 minutes per each lb of the ham roast you're cooking.
Preheat the oven to 350 F and cook the ham in a shallow roasting pan.
If your ham is a 5 lb ham then you'd cook it for 100 minutes and for a 10 lb ham you'd cook the 10 lb ham for 200 minutes.
The ham will be fully cooked when a meat thermometer reads 140 F for the hams internal temperature.