Pearson Edexcel International GCSE Economics: Scarcity, the PPF and assumptions (4EC1) – Revision Notes

These notes condense sections 1.1.1 and 1.1.2 of the Pearson Edexcel International GCSE Economics (4EC1) specification, Issue 3, February 2026, a single-tier qualification. For full explanations read the study guide, then test yourself with the practice questions. Other links: the course hub, the checklist, the market system revision notes and the free diagnostics. Every figure on this page is invented and illustrative.

Key terms

Term	Definition to learn
Scarcity	Wants are unlimited but resources are finite, so choices must be made
Opportunity cost	The value of the best alternative sacrificed by making a choice
Production possibility frontier (PPF)	A curve showing the most of one good an economy can make for each level of the other good, with all resources in use
Economic growth	An increase in the economy’s productive potential, shown as an outward shift of the PPF
Maximise benefit	A consumer aims for the greatest satisfaction from spending
Maximise profit	A business aims for the greatest gap between revenue and cost

1.1.1 a-b: Scarcity and opportunity cost

• Scarcity comes from unlimited wants and finite resources. It affects rich and poor countries alike.
• Scarcity forces a choice, and every choice has an opportunity cost.
• Opportunity cost is one item: the best alternative forgone.

Method for opportunity cost.

1. List the options.
2. Rank them.
3. Find the choice made.
4. Name the next best option as the cost, with its value if given.

Agent	Typical choice	Opportunity cost
Consumer	Spend limited income on one item	The next best item that income could have bought
Producer	Invest limited funds in one project	The return from the next best project
Government	Spend a limited budget in one area	The next best spending area or a tax cut

Worked reminder (consumer). Lena has 60 units. Her ranking is headphones (60), a deposit on a weekend trip (60), or two pairs of jeans (30 each). She buys the headphones. The opportunity cost is the trip deposit, not the jeans as well.

Worked reminder (producer). A farm has 12,000 units. A tractor adds 1,800 a year and irrigation adds 1,200 a year. Return on the tractor is 1,800 ÷ 12,000 × 100 = 15%, on irrigation 1,200 ÷ 12,000 × 100 = 10%. Choosing the tractor gives up 1,200 a year.

Worked reminder (government). A budget of 150 million can fund five clinics at 30 million each (5 × 30 = 150) or 25 km of rail at 6 million per km (25 × 6 = 150). Choose rail and five clinics are forgone.

1.1.1 c-d: The PPF

Country C makes laptops and wheat (thousands).

Laptops	Wheat	Opportunity cost of extra laptops
0	60	–
5	56	4 wheat for 5 laptops = 0.8 each
10	48	8 for 5 = 1.6 each
15	30	18 for 5 = 3.6 each
20	0	30 for 5 = 6.0 each

Opportunity cost per laptop rises, so the curve bows outwards. A straight line means a constant opportunity cost.

Sketch. Wheat on the vertical axis, laptops on the horizontal axis, a smooth curve from (0, 60) to (20, 0), both axes labelled, the curve labelled PPF.

What each position means

Position	Meaning	Example
On the curve	Maximum productive potential, resources fully employed	(10, 48)
Inside the curve	Possible, but resources unemployed or underused	(10, 40)
Outside the curve	Unobtainable with present resources	(15, 45)

For (10, 40): the curve gives 48 wheat at 10 laptops, so 48 − 40 = 8 wheat of potential is unused. That is 8 ÷ 48 × 100 = 16.7% below potential.

Shifts

• Outward shift = positive growth. A 10% rise in capacity moves the intercepts from 60 wheat to 66 and from 20 laptops to 22.
• Inward shift = negative growth. Capacity falls.
• Moving along the curve is a change of mix. Moving from inside to the curve is using idle resources, not growth.
• One-sided change: better wheat technology raises the wheat intercept only, and the laptop intercept stays at 20.

1.1.1 e: Causes of growth and decline

Positive (outward)	Negative (inward)
More labour, land or capital	Fewer workers, depleted resources
Better education and training	Loss of skills
Investment in machinery and infrastructure	War, flood or earthquake damaging capital
Better technology	Lost access to technology or trade

Chain of reasoning. Cause, then what changes in resources (quantity or quality), then output of both goods rises or falls, then the PPF shifts.

1.1.2: Assumptions

• Consumers aim to maximise their benefit.
• Businesses aim to maximise their profit.

Consumers may not maximise benefit because of:

• poor calculation of benefits and costs, such as ignoring unit prices
• habits that are hard to give up, such as a daily purchase
• copying others, such as buying what friends or influencers buy

Producers may not maximise profit because of:

• managers who maximise revenue or sales
• caring for customers, for example by keeping prices fair or giving free support
• charitable work, for example donating goods

Worked reminder (profit versus revenue). A market stall sells T-shirts.

Output	Revenue	Cost	Profit
2	80	60	20
4	140	90	50
6	180	120	60
8	200	190	10

Profit is highest at 6 shirts (60). Revenue is highest at 8 (200) but profit is only 10. A revenue or sales-maximising manager picks 8 and gives up 50 of profit.

Evaluation prompts

The specification lists Evaluate as a command word that asks for a supported conclusion. For this unit, practise short lines like these.

• Is the profit assumption reasonable? Yes for a firm facing tough rivals, since survival needs profit. Less so for a manager paid on sales, or a firm with a social aim. The judgement depends on who owns and runs the business.
• Are consumers rational? Often close to it for big, rare purchases where people compare prices. Less so for small, repeated or fashion-led purchases. The assumption is a simplification that still predicts general patterns.
• Which cause of growth matters most? Investment and technology tend to raise output for many years, while a discovery of resources may be one-off. Whether growth lasts depends on whether the extra output is used and kept.
• Does growth remove scarcity? No. The curve moves out, but wants rise too, so choices and opportunity costs remain.

Command words to recognise. The specification says What is meant by needs two separate parts to the definition, Calculate expects workings, and Draw expects a diagram with separate awardable points. Always label axes and curves.

Must-know distinctions

• Scarcity versus shortage: scarcity is permanent, a shortage is at one price.
• Opportunity cost versus money cost: the price paid is not the opportunity cost.
• Inside the PPF versus outside: inside is wasteful but possible, outside is unobtainable.
• Movement versus shift: choice moves you along, growth shifts the curve.
• Revenue versus profit: revenue is price times quantity, profit is revenue minus cost.

Quick self-test

1. What is meant by scarcity?
2. A student ranks a game (45 units), a cinema trip (45) and shoes (45) in that order, and buys the game. What is the opportunity cost?
3. In the Country C table, how much wheat is lost moving from 10 to 15 laptops, and what is the cost per laptop?
4. Country C produces 10 laptops and 40 wheat. Is this possible, and what does it show?
5. Country C capacity rises by 10%. State the new maximum wheat output.
6. Give two causes of an inward shift of the PPF.
7. A government has a budget of 150 million and chooses rail instead of clinics. What is the opportunity cost?
8. State two reasons why consumers may not maximise their benefit.
9. In the T-shirt table, which output maximises profit?
10. Give two ways a firm might not maximise profit.

Answers

1. Wants are unlimited but resources are finite, so choices must be made.
2. The cinema trip, as the next best alternative.
3. 48 − 30 = 18 wheat, which is 18 ÷ 5 = 3.6 wheat per laptop.
4. It is possible but inside the curve (48 wheat is possible at 10 laptops), so resources are unemployed or underused, by 8 wheat or 16.7%.
5. 60 × 1.1 = 66.
6. For example war or a natural disaster destroying capital, or workers leaving the country.
7. The five clinics.
8. For example habits that are hard to give up, and copying others.
9. 6 shirts, with profit of 60.
10. For example managers maximising revenue, or charitable work.

Where marks are usually lost

• Giving a list of all alternatives as the opportunity cost.
• Stating the price instead of the thing given up.
• Drawing a PPF with a straight line when the question describes rising costs, or leaving axes unlabelled.
• Describing a point inside the curve as unobtainable.
• Showing growth as a move along the curve.
• Naming a cause of growth without saying what it does to resources or output.
• Writing “consumers are irrational” without a specific reason such as habit.
• Stating a numerical answer with no working or no units where the question says “Calculate”.

Official syllabus

Pearson Edexcel International GCSE in Economics (4EC1) specification, Issue 3, February 2026, for first teaching September 2017, published by Pearson Education Limited, sections 1.1.1 and 1.1.2.