Acid rain-rain with a pH value less than 5.7, caused by the reaction of certain air pollutants with rainwater-is a growing problem in the United States. Pure rain falling through clean air registers a PH value of 5.7 (PH is a measure of acidity: 0 is acid; 14 is alkaline). A sample of n = 30 rainfalls produced PH readings with x = 3.6 and s = 0.4. Do the data provide sufficient evidence to indicate that the mean ph for rainfalls is more acidic (H_: ( 5.7 O H: u = 5.7 versus H_: u 5.7 versus H : u