A lone person fishing at a lake can catch 10 fish per day. Each additional person fishing at the lake reduces the catch per person by one fish per day. If a person would rather stay home than catch fewer than four fish (i.e., the opportunity cost of going to the lake is four fish), how many people will show up each day to fish at the lake? What are the net benefits to society of this outcome? What is the efficient number of people fishing to show up at the lake? Is access to the lake a public good?