Two consumers have demand curves d_1(p) = 12 - p (zero at any price a… | Economics CUET question

Two consumers have demand curves \( d_1(p) = 12 - p \) (zero at any price above 12) and \( d_2(p) = 18 - 2p \) (zero at any price above 9). Which of the following statements are correct?

(A) At p = 6, the market demand is 6 units.
(B) At p = 12, the market demand is 0 units.
(C) At p = 4, the market demand is 18 units.
(D) At p = 10, the market demand is 2 units.
(E) The market demand is 30 – 3p at every price.

Choose the correct answer from the options given below:

Answer & explanation

Correct answer: option 3

The correct answer is Option (3) → (B), (C) and (D) only

Market demand at a price is the sum of both consumers’ demands at that price.

(A) At p = 6, the market demand is 6 units. — Incorrect. d₁ = 12 − 6 = 6 and d₂ = 18 − 12 = 6, so market demand is 12.

(B) At p = 12, the market demand is 0 units. — Correct. d₁ = 12 − 12 = 0, and d₂ = 0 above Rs 9.

(C) At p = 4, the market demand is 18 units. — Correct. d₁ = 8 and d₂ = 18 − 8 = 10, so 8 + 10 = 18.

(D) At p = 10, the market demand is 2 units. — Correct. d₁ = 2 and d₂ = 0 above Rs 9.

(E) The market demand is 30 – 3p at every price. — Incorrect. 30 − 3p holds only up to Rs 9; above Rs 9 only consumer 1 buys.

NCERT (2026-27): “2.5 Market Demand … The market demand for a good at a particular price is the total demand of all consumers taken together. … Thus, the market demand for the good at each price can be derived by adding up the demands of the two consumers at that price. If there are more than two consumers in the market for a good, the market demand can be derived similarly. …”

“Adding up Two Linear Demand Curves … Furthermore, at any price greater than 10, the consumer 1 demands 0 unit of the good, and similarly, at any price greater than 15, the consumer 2 demands 0 unit of the good. The market demand can be derived by adding equations (2.14) and (2.15). At any price less than or equal to 10, the market demand is given by 25 – 2p, for any price greater than 10, and less than or equal to 15, market demand is 15 – p, and at any price greater than 15, the market demand is 0.”