Researchers want to compare the effects of knee arthroscopy, a surgery for osteoarthritis, to the effects of exercise therapy. In a random sample of 800 patients who received the surgery, 280 saw benefits a year later. In a random sample of 250 patients who were asked to complete exercise therapy, 120 saw benefits a year later. Construct a 95% confidence interval for (Pexercise Psurgery), the difference in how effective the two treatments are.