With capital held constant, the marginal product of the Lth unit of labour is measured as:
Answer & explanation
Correct answer: option 3
The correct answer is Option (3) → (TP at L units) – (TP at L – 1 units)
Marginal product is the extra output from one more unit of labour, capital held constant. So MP of the Lth unit is TP at L units minus TP at L − 1 units.
Option (1) (TP at L + 1 units) – (TP at L – 1 units) — Incorrect. This difference spans two units of labour, not one.
Option (2) the sum of the TP of every unit of labour up to L — Incorrect. Adding up TP figures does not measure the extra output of one unit. It is the sum of the marginal products that gives TP.
Option (3) (TP at L units) – (TP at L – 1 units) — Correct. It is the change in TP from one more unit of labour.
Option (4) (TP at L units) ÷ L — Incorrect. TP divided by L is the average product.
NCERT (2026-27): “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. …” “3.3.3 Marginal Product … For example, when L changes from 1 to 2, TP changes from 10 to 24. MPL= (TP at L units) – (TP at L – 1 unit) Here, Change in TP = 24 -10 = 14 Change in L = 1 Marginal product of the 2nd unit of labour = 14/1 = 14” |