Capital is held fixed. The average product of labour is 15 units with 4 workers and 14 units with 5 workers. The 6th worker adds 8 units of output. What are the marginal product of the 5th worker and the average product with 6 workers?
Answer & explanation
Correct answer: option 4
The correct answer is Option (4) → MP of the 5th worker = 10 units; AP with 6 workers = 13 units
Given:
AP with 4 workers = 15 units
AP with 5 workers = 14 units
MP of the 6th worker = 8 units
Total product = AP × number of workers.
\( TP_4 = 15 \times 4 = 60 \)
\( TP_5 = 14 \times 5 = 70 \)
\( MP_5 = 70 - 60 = 10 \) units
\( TP_6 = 70 + 8 = 78 \)
\( AP_6 = 78 / 6 = 13 \) units
Option (1) MP of the 5th worker = 10 units; AP with 6 workers = 11 units — 11 is the average of 14 and 8, not TP divided by 6.
Option (3) MP of the 5th worker = –1 unit; AP with 6 workers = 13 units — this takes the change in AP (15 − 14 = 1); MP is found from the totals.
NCERT (2026-27): “3.3.2 Average Product Average product is defined as the output per unit of variable input. … Values in this column are obtained by dividing TP (column 2) by L (Column 1). …” “3.3.3 Marginal Product Marginal product of an input is defined as the change in output per unit of change in the input when all other inputs are held constant. …” |