Recreation centers offer a place for young people to play sports and engage in other activities at a marginal cost of MC = 0. 3Q. The inverse demand curve for recreation centers is given by P = 10 - 0. 2@, where P is the price of entry and Q measures hundreds of entrants. Recreation centers generate positive externalities because they help get young people engaged in productive activities. The external marginal benefits are EMB = 2 + 0. 02Q. The socially optimal number of entrants is entrants. 2,000 2,500 3,000 3,500