2)

The Environmental Protection Agency (EPA) is charged with monitoring "acid rain," a term

for the fall of water through an acidic atmosphere. Acidity is measured on the pH scale, where

pure water has a pH of 7.0. Normal rain is slightly acidic because of atmospheric carbon dioxide,

and has a pH of about 5.5 (lower pH indicates greater acidity). Suppose the EPA wishes to

determine whether a particular area is subject to acid rain. Let

denote the true average for pH

in this area.

(a) What is the appropriate null hypothesis in this study?

(b) What is the appropriate alternative hypothesis in this study?