147 Alkalinity of river water. The mean alkalinity level of water specimens collected from the Han River in Seoul, Korea, is 50 milligrams per liter ( Environmental Science

& Engineering , September 1, 2000). Consider a random sample of 100 water specimens collected from a tributary of the Han River. Suppose the mean and standard deviation of the alkalinity levels for the sample are, respectively, x = 67.8 mpl and s = 14.4 mpl. Is there sufficient evidence

(at a = .01 ) to indicate that the population mean alkalinity level of water in the tributary exceeds 50 mpl?