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PPF and Opportunity Cost Class 11 Economics Solved

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EconomicsCBSE Class 11 · Introduction

Production Possibility Frontier, Opportunity Cost and Marginal Rate of Transformation

Updated 17 October 2026 · Fact-checked

The production possibility frontier (PPF) shows the maximum combinations of two goods an economy can produce with given resources and technology. Opportunity cost is the value of the next best alternative given up; marginal opportunity cost (MRT) is the loss of one good per additional unit of the other. A concave PPF reflects an increasing MRT; growth in resources or technology shifts it outward.

Points on the curve use all resources; inside wastes them, outside is unattainable, and the curve bows out because each extra tonne of rice costs more cloth.

Illustration drawn for QuestionBuddy.

Understand Production Possibility Frontier and Opportunity Cost

Scarcity and choice. Resources are limited, wants are unlimited, and resources have alternative uses; therefore every economy must choose what, how and for whom to produce. Opportunity cost of a choice is the value of the next best alternative given up.

PPF (production possibilities curve). A curve showing all maximum combinations of two goods that can be produced when resources are fully and efficiently used and technology is given. Assumptions: fixed resources, given technology, full employment and efficient use.

Worked schedule (rice and cloth).
| Combination | Rice (tonnes) | Cloth (metres) | MOC = loss of cloth per tonne of rice |
| A | 0 | 40 | |
| B | 10 | 36 | 4/10 = 0.4 |
| C | 20 | 28 | 8/10 = 0.8 |
| D | 30 | 16 | 12/10 = 1.2 |
| E | 40 | 0 | 16/10 = 1.6 |
Moving from A to D (0 to 30 tonnes of rice), the opportunity cost is 40 − 16 = 24 metres of cloth.

Marginal opportunity cost (MOC) / marginal rate of transformation (MRT) = loss of output of one good per unit gain of the other = ΔY ÷ ΔX (without sign). It rises along the table: 0.4, 0.8, 1.2, 1.6.

Shape. The PPF is concave to the origin because the MRT increases: resources are not equally suited to both goods; as more rice is produced, resources better suited to cloth must be shifted, so more cloth is lost for each extra tonne of rice. If resources were equally productive in both uses, MOC would be constant and the PPF a straight line.

Points relative to the PPF.

  • On the curve: efficient and full use.
  • Inside (e.g. 20 rice, 20 cloth, when the frontier gives 28 cloth at 20 rice): underutilisation or unemployment of resources (inefficiency).
  • Outside (e.g. 25 rice, 30 cloth; the frontier cannot reach it): unattainable with present resources and technology.

Shifts of the PPF. Outward: increase in resources (more labour, capital) or better technology: economic growth. Inward: loss of resources (disaster, war). Rotation: technology better for only one good. A movement along the PPF is a change in product mix (reallocation), not growth.

Central problems. The PPF illustrates scarcity (the frontier limits output), choice (movement along it) and opportunity cost (the slope).

Draw and label: the PPF with points A to E, a point inside and a point outside, and an outward shift.

Production Possibility Frontier and Opportunity Cost: key facts

MOC / MRT
Loss of good Y / gain of good X
Slope of the PPF
Opportunity cost
Value of the next best alternative given up
Cost of choice
Concave PPF
MRT rises as more X is produced
Resources not equally suited
Shift
Outward: growth | inward: loss of resources
Not a movement along

How to answer Production Possibility Frontier and Opportunity Cost questions

Questions give a schedule and ask for MOC, a point status or the effect of a change.

  1. 1Compute MOC as the fall in Y divided by the rise in X between neighbouring rows.
  2. 2If MOC rises, say the PPF is concave.
  3. 3Compare a given point with the frontier at the same X to classify it.
  4. 4Distinguish movement along the PPF from a shift.
  5. 5Name the cause of any shift.

Production Possibility Frontier and Opportunity Cost in real life

The idea, met in an everyday situation. Answer the question in your own words, then compare with the model answer. The one-line hook is what to remember.

Farmer's plot

Suppose a farmer can use a 2-hectare plot for rice or cloth-yielding cotton: rows of the table from A to E show the trade-off.

What is the cost, in cloth, of raising rice from 20 to 30 tonnes?

Try it first, then show the solutionSolution
  1. At 20 tonnes of rice cloth is 28 metres; at 30 tonnes it is 16.
  2. Cloth lost = 28 - 16 = 12 metres.
  3. MOC = 12 / 10 = 1.2 metres of cloth per tonne of rice.

Answer: 12 metres of cloth; MOC 1.2.

Memory hook: Every extra tonne costs cloth.

Tricks to remember Production Possibility Frontier and Opportunity Cost

Short memory aids. Say each one aloud once, then use it on a question the same day.

  • More X, more cost

    Concave PPF: rising opportunity cost.

    Use it when: Shape

  • Inside = idle

    Inside the PPF means unemployment.

    Use it when: Points

  • Out = grow

    Outward shift = growth.

    Use it when: Shift

Production Possibility Frontier and Opportunity Cost: solved examples

Ordered from board level to HOTS. Try each one before you open the solution.

Example 1: Opportunity cost · 2 marks · Very short answerBoard level

Define opportunity cost and find the opportunity cost of producing 30 tonnes of rice instead of none in the schedule.

Try it first, then show the solutionSolution
  1. Opportunity cost is the value of the next best alternative given up (1 mark).
  2. Cloth falls from 40 to 16, so 24 metres of cloth is given up (1 mark).

Answer: 24 metres of cloth.

Example 2: MOC · 3 marks · Short answerBoard level

Calculate the marginal opportunity cost of rice between each pair of combinations A to E.

Try it first, then show the solutionSolution
  1. A to B: 4/10 = 0.4 (1 mark).
  2. B to C: 8/10 = 0.8; C to D: 12/10 = 1.2 (1 mark).
  3. D to E: 16/10 = 1.6; MOC rises (1 mark).

Answer: 0.4, 0.8, 1.2, 1.6.

Example 3: Shape of PPF · 3 marks · Short answerHarder board level

Use the MOC figures of the schedule to explain the shape of the PPF, and say what a constant MOC would imply.

Try it first, then show the solutionSolution
  1. MOC increases as more of one good is produced (1 mark).
  2. Resources are not equally suited to both goods, so moving them lowers output in the other use more and more (1 mark).
  3. If resources were equally productive in both uses, MOC would be constant and the PPF a straight line (1 mark).

Answer: Increasing MOC; constant MOC gives a line.

Example 4: Classify the points · 3 marks · Short answerHarder board level

Using the schedule, classify (a) 20 rice and 20 cloth (b) 25 rice and 30 cloth (c) 20 rice and 28 cloth.

Try it first, then show the solutionSolution
  1. (a) At 20 rice the frontier gives 28 cloth, so 20 is inside: attainable but resources are underutilised (1 mark).
  2. (b) At 25 rice the frontier gives less than 28 cloth, so 30 is outside: unattainable (1 mark).
  3. (c) On the frontier: full and efficient use (1 mark).

Answer: Inside; outside; on.

Example 5: Effects of changes · 5 marks · Long answerHOTS / competency

Suppose a new seed raises rice output per hectare but cloth technology is unchanged, and later a flood destroys farmland. Explain the effect of each on the PPF and what each shows about growth and the central problem.

Try it first, then show the solutionSolution
  1. Seed: the rice end of the PPF moves out, so the curve rotates outward at the rice end (1 mark).
  2. Cloth end is unchanged, so only the maximum rice rises (1 mark).
  3. This is growth through improved technology, easing scarcity for rice (1 mark).
  4. Flood: the PPF shifts inward as productive resources are lost (1 mark).
  5. The economy can produce less of both goods and the choice problem remains (1 mark).

Answer: Rotation outward; then inward shift.

Where students lose marks in Production Possibility Frontier and Opportunity Cost

The slips examiners see most often, and what to write instead.

  • Mistake: Inside the PPF as growth

    Confusion.

    Wrong working

    Moving to the PPF from inside is growth.

    Right working

    It is better use of resources, not growth.

    Do this: Growth is a shift.

    Usually costs: 1 mark.

  • Mistake: MOC as total loss

    Marginal vs total.

    Wrong working

    MOC from A to E is 40.

    Right working

    MOC is loss per unit gain of the other good.

    Do this: Per unit.

    Usually costs: 1 mark.

  • Mistake: Straight PPF always

    Shape ignored.

    Wrong working

    PPF is a straight line.

    Right working

    PPF is concave when MOC rises.

    Do this: Increasing MOC.

    Usually costs: 1 mark.

Exam tips

  • Show MOC calculations row by row.
  • State assumptions of the PPF.
  • Classify points by comparing at the same X.
  • Differentiate movement and shift.

Practice questions on Production Possibility Frontier and Opportunity Cost

Write each answer on paper first. Open the hint only if you are stuck, and the answer only when you have finished.

  1. Q1 · 1 mark · MCQBoard level

    An economy operating inside its PPF is
    (a) fully employing resources (b) underutilising resources (c) experiencing growth (d) producing at maximum efficiency

    Hint

    Idle resources.

    Answer

    (b).

  2. Q2 · 1 mark · Assertion-reasonHarder board level

    Assertion (A): The PPF shifts outward when technology improves.
    Reason (R): Better technology raises the maximum output attainable from given resources.
    (a) Both A and R are true and R is the correct explanation of A.
    (b) Both A and R are true but R is not the correct explanation of A.
    (c) A is true but R is false.
    (d) A is false but R is true.

    Hint

    Growth.

    Answer

    (a).

  3. Q3 · 2 marks · Very short answerBoard level

    What does the slope of the PPF measure, and what happens to it as more of X is produced on a concave PPF?

    Hint

    MRT.

    Answer

    It measures the marginal rate of transformation (MOC), the amount of Y given up per unit of X; on a concave PPF it rises (becomes steeper).

  4. Q4 · 4 marks · Case-basedHarder board level

    Read and answer.
    Suppose an economy moves from combination C (20, 28) to B (10, 36) on the schedule.
    (a) What happens to rice and cloth? (1)
    (b) Find the opportunity cost of the extra cloth. (1)
    (c) Is this growth? (2)

    Hint

    Movement along.

    Answer

    (a) Rice falls from 20 to 10 and cloth rises from 28 to 36. (b) 10 tonnes of rice are given up for 8 metres of cloth, 1.25 tonnes per metre. (c) No, it is a movement along the PPF (change of product mix), not growth.

  5. Q5 · 3 marks · Short answerHOTS / competency

    Suppose a country finds oil, which raises its output of fuel but not of food. Explain the PPF with fuel and food, why it is not a parallel shift, and how this relates to the opportunity cost of food.

    Hint

    Rotation.

    Answer

    The maximum fuel output increases while the maximum food output stays, so the PPF swivels outward on the fuel axis, not a parallel shift. The opportunity cost of food in terms of fuel changes because the slope changes.

Test your recall

Answer in your head or on paper first, then open the card. Pulling an answer out of memory makes it stick far better than re-reading.

  1. 1.PPF assumption?Show answer

    Given resources and technology.

  2. 2.Concave means?Show answer

    Rising MOC.

  3. 3.Inside the PPF?Show answer

    Underutilised resources.

  4. 4.Growth shows as?Show answer

    Outward shift.

  5. 5.MRT formula?Show answer

    Delta Y / Delta X.

  6. 6.Opportunity cost?Show answer

    Next best alternative given up.

Production Possibility Frontier and Opportunity Cost: frequently asked questions

What is a PPF?

Curve of maximum output combinations.

What is MRT?

Marginal rate of transformation.

Why a concave PPF?

Increasing opportunity cost.

What shifts it?

Resources or technology.

What is scarcity?

Limited resources versus unlimited wants.