JAMB 2015 Economics · Question 67

c c Units of variable factor Total Product 1 25 2 31 3 40 4 48 5 55 The marginal product at the fifth variable…

Question

$\begin{array}{c|c} \text{Units of variable factor} & \text{Total Product} \\ \hline 1 & 25 \\ \hline 2 & 31 \\ \hline 3 & 40 \\ \hline 4 & 48 \\ \hline 5 & 55 \\ \end{array}$ The marginal product at the fifth variable factor is

Answer: A. 7

Explanation written with AI and checked against the answer key

Analyze the question: We are asked for the marginal product (MP) of the 5th unit of the variable factor. Concept: Marginal product is the extra output gained by adding one more unit of the variable factor: MP = change in Total Product ÷ change in units of variable factor MPₙ = TPₙ − TPₙ₋₁ Solution: | Units | TP | MP | |---|---|---| | 1 | 25 | 25 | | 2 | 31 | 6 | | 3 | 40 | 9 | | 4 | 48 | 8 | | 5 | 55 | 7 | For the 5th unit: MP₅ = TP₅ − TP₄ = 55 − 48 = 7 Answer: A. 7 Tip: For marginal product (or marginal cost or revenue) questions, subtract the previous total from the current total. Always check which unit the question asks about. Option B (6) is the MP of the 2nd unit, and option D (9) is the MP of the 3rd unit, so these are common traps if you pick the wrong row.

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