
Ten homeowners live around Lake Alice. Unfortunately, the lake is contaminated with various chemicals and the level of contamination is currently 20 parts per million. All the homeowners benefit equally if the level of contamination is reduced. The table above gives the marginal cost and marginal benefit for removing the contaminants from the lake.
a. What will be the parts per million if the homeowners alone are in charge of reducing the contaminants?
b. What is the efficient amount of contamination?