Okay, here's the secret formula for "Method X" - Multiply the exact weight times 5 minutes. This is the cooking time (you can round the cooking time up to the nearest minute).
For me it was 3.75 lbs x 5 min. = 18.75 minutes or 19 minutes
Be sure to get the exact weight from the label and don't round!
Preheat your oven to 500 degrees F. Be sure the oven is given time to preheat fully. It must be up to temperature when the prime rib is put in.
Place the prime rib on the middle rack and roast for EXACTLY the number of minutes determined by the formula above. Then turn the oven off. DO NOT OPEN THE DOOR.