2. Efficiency in the presence of extemalities Public wifi hotopots grant many external benefits on socicty: more equitable access to the internct, increased educational opportunities, and so on. Therefore, the markot equilibrium quantity of public wif hotepots does not equal the socially optimal quantity. The following graph plots the demand for public wifi hotspots (their private value), the supply of public wifi hotspots (the privite cost of producing them), and the sodal value of public wifi hotspots, including both the private value and external benefits, Use the black point (olus symbol) to indicate the markot aquhibrwam quanthy; Next, use the purple povint (charmond symbol) fo indicate the socaily optimal quanitity..