JAMB Economics 2023 Paper

Concept:Marginal utility is the extra satisfaction gained from consuming one additional unit of a good.Explanation:Marginal utility is calculated as:$$MU = TU_n - TU_{n-1}$$Where $TU_n$ is the total utility of the current unit and $TU_{n-1}$ is the total utility of the previous unit.For the second orange, total utility of 2 oranges is $16$ and total utility of 1 orange is $9$.Therefore, the marginal utility $X$ is:$$X = 16 - 9 = 7$$Answer:$X = 7$Correct option: B. 7