JAMB Economics 2015 Paper

Concept:Utility is maximized when the consumer stops buying a product at the point where the extra satisfaction gained equals the price paid for it.Explanation:For product $X$, the consumer gains while $\mathrm{MU}_X > P_X$, so they continue to buy more units.When $\mathrm{MU}_X < P_X$, the consumer is overpaying relative to the satisfaction received, so they buy less.The best position is therefore reached when the marginal utility of product $X$ is exactly equal to its price.That gives the equilibrium condition:$$\mathrm{MU}_X = P_X$$This is the point where total utility is maximized for the consumer.No other option represents this standard utility-maximizing rule.Answer:B. $\mathrm{MU}_X = P_X$