Suppose that an NGO provides medical treatments to prevent the spread of an epidemic. It can prevent 72q 1/2 infections by providing q medical treatments. Each treatment costs $4. The NGO aims to maximize its surplus, which is defined as: Surplus (q) = (72q1 /2) - (49). The surplus-maximizing number of treatments, q * , that the NGO should provide is The number of infections the NGO's efforts prevent when it provides q * treatments is equal to