Imagine a market where there is a positive externality in production. The private (and social) inverse demand function for the good is: D_private: P_D = 20 - 1.5Q D. The private inverse supply function is: S_private: P_S = 4 + 0.5Q_S. The social inverse supply function that accounts for the positive externality in production is: S_social: P_S = 2 + 0.5Q_S. What is the market equilibrium (as opposed to the social optimum) quantity for the good