Acid rain from the burning of fossil fuels has caused many of the lakes around the world to become acidic. the biology in these lakes often collapses because of the rapid and unfavorable changes in water chemistry. a lake is classified as nonacidic if it has a ph greater than 6. a. marchetto and a. lami measured the ph of high mountain lakes in the southern alps and reported their findings in the paper "reconstruction of ph by chrysophycean scales in some lakes of the southern alps" (hydrobiologia, vol. 274, pp. 83-90). data set 1 shows the ph levels obtained by the researchers for 15 lakes. at the 5% significance level, do the data provide sufficient evidence to conclude that, on average, high mountain lakes in the southern alps are nonacidic? apply the one-mean t-test.