Naproxen, a generic anti-inflammatory, claims to have, on average, at least 50 milligrams of active ingredient. An independent lab tests a random sample of 75 tablets and finds the mean content of active ingredient in this sample is 46.6 milligrams with a standard deviation of 9 milligrams. If the lab doesn't believe the manufacturer's claim that the average active ingredient is at least 50 milligrams, what is the approximate p-value for the suitable test?