how to figure out cooking time I seared by prime rib at 450 degrees for 30 minutes and then I was supposed to reduce the temp to 325 for an additional 3 hours.  I forgot to turn down the temperature and caught my mistake 25 minutes into cooking.  How much time should I reduce my cooking by?
It's hard to tell, since it depends on a lot of different factors. I would estimate that you should reduce the cooking time by about 20 minutes. For the future, I would recommend investing in a meat thermometer. Then you can tell when the meat is done without relying on oven temperatures and times.