(1 point) The EPA wants to test a randomly selected sample of water specimens and estimate the mean daily rate of pollution produced by a mining operation. If the EPA wants a 80% confidence interval with a bound of error of 1.5 milligram per liter (mg/L), how many water specimens are required in the sample? Assume prior knowledge indicates that pollution readings in water samples taken during a day have been approximately normally distributed with a standard deviation of 3 (mg/L). n =