For some reason people care about how acidic fresh water is. Tworesearchers conducted a study of
15 mountain lakes in the Southern Alps; any lake that has a pHgreater than 6 would be classfied as
"non-acidic." Below is a table of the pH levels from the 15lakes the researchers surveyed:
pH values of 15 Alpine Lakes
7.2 7.3 5.7
7.3 6.3 6.9
6.1 5.5 6.7
6.9 6.3 7.9
6.6 6.5 5.8
The standard deviation of the sample is given as: S = 0:672. Atthe 5% -level, does this sample
provide sufficient evidence to conclude that, on average, highmountain lakes in the Southern Alps are
non-acidic? State both null and alternative hypotheses,calculate and interpret your test statistic.
