JAMB Economics 2024 Paper

Concept:Marginal product is the change in total product caused by one extra unit of input.When total product begins to fall, that change becomes negative.Explanation:Total product ($TP$) rises as long as each additional worker adds more output.At the point where $TP$ is maximum, marginal product ($MP$) equals zero.After this peak, $TP$ starts falling.This happens because extra input now reduces output, often due to inefficiency.Mathematically, $MP = \frac{\Delta TP}{\Delta \text{input}}$.Since $\Delta TP$ is negative when $TP$ decreases, $MP$ must also be negative.Therefore, the falling stage of total product corresponds to negative marginal product.Answer:D. negative