JAMB 2015 Economics · Question 7

c c Units of labour Fixed capital Total product Average product Marginal product 0 10 - - - 1 10 10 10 10 2 10…

Question

$\begin{array}{c|c} \text{Units of labour} & \text{Fixed capital} & \text{Total product} & \text{Average product} & \text{Marginal product} \\ \hline 0 & 10 & - & - & - \\ \hline 1 & 10 & 10 & 10 & 10 \\ \hline 2 & 10 & 25 & ? & 15 \\ \hline 3 & 10 & 50 & 16.7 & 25 \\ \hline 4 & 10 & 80 & 20.0 & 30 \\ \hline 5 & 10 & 106 & 21.2 & 26 \\ \end{array}$ Calculate the average product when the 2nd labour was employed 12.5

A.12.5
B.12
C.15
D.10

Answer: A. 12.5

Explanation written with AI and checked against the answer key

Analyze the question: You are asked for the average product (AP) when 2 units of labour are employed. The table gives total product (TP) = 25 at 2 units of labour.

Concept: Average product is total product divided by the number of units of labour:

AP = TP ÷ units of labour

Solution:

AP at 2 labour units = 25 ÷ 2 = 12.5

Check against the table:

At 1 unit: 10 ÷ 1 = 10 ✓
At 3 units: 50 ÷ 3 = 16.7 ✓
At 4 units: 80 ÷ 4 = 20.0 ✓
At 5 units: 106 ÷ 5 = 21.2 ✓

The pattern holds, so the value of 12.5 fits the table.

Answer: The average product is 12.5, which is option A.

Tip: Don't confuse AP with MP. AP = TP ÷ labour, while MP = change in TP ÷ change in labour. Here the MP at 2 units is 25 − 10 = 15, which is option C. That is a trap, because it is the marginal product, not the average. Always check which one the question asks for.

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