Basic Economic Problem & the PPC

— Economics · A Level · Microeconomics (last micro chapter) —

★ Exam Tip: The first half (agents, fundamental questions, factors of production) is mostly MCQ material. The PPC is the real scoring part — an 8-mark essay like “Analyse using a PPC diagram, explain the difference between actual and potential economic growth” comes from here. Always draw the diagram first, then explain it.

1. What is the Basic Economic Problem?

Basic economic problemwants are UNLIMITED but resources are LIMITED

the whole basic economic problem in one line

Scarcity = shortage of resources (because resources can never satisfy all wants). Because of scarcity people must make a choice, and a choice has a price → opportunity cost.

Remember: the problem never ends — it affects every individual and every economy. It is normal!

Wants keep changing: iPhone 8 → 11 → 13 → 15 → 16 … always want the next one.
A millionaire wants to be a billionaire; a billionaire wants to be a trillionaire.
So wants never finish, resources are always limited ⇒ always feel “I have less”.

Opportunity cost = the next best alternative foregone (given up)

Whatever you leave / let go of when you choose = your opportunity cost. At every moment of life there is one.

Examples:

Rest or attend class → if you rest, taking the class is the OC.
Go to a wedding in your own car or with a friend → own car: OC = arriving late / missing the food (sir’s example).
Student: work in a grocery shop or complete education → study ⇒ OC = money earned; earn ⇒ OC = school / college.

2. Economic Agents & their Opportunity Cost

The people who face opportunity cost are called economic agents. There are 3: consumer, producer, government.

Agent	Has limited…	Chooses between	Opportunity cost
Consumer	income	good X or good Y	units of the other good not bought
Producer	capital	capital goods or consumer goods	the good not produced
Government	funds	public goods or subsidy to a declining industry	the one not provided

Why OC? Consumer – limited income · Producer – limited capital · Govt – limited funds ⇒ none can have both ⇒ all three bear OC. Relation between the two choices = negative (more of one ⇒ less of the other).

Note: The basic economic problem is faced by all economies and all individuals.

3. The Three Fundamental Questions

① WHAT to produce?
② HOW to produce?
③ FOR WHOM to produce?

(these three are written at the start of the book — what to make, how to make it, who it is made for)

4. Factors of Production (FOPs)

Definition: FOPs are the resources used to produce goods and services. There are 4: land, labour, capital, entrepreneur.

FOP	What it is	Examples	Reward / cost
Land	natural resource	farmland, forest, air, water — every natural resource	rent
Labour	human resource	workers (skilled & unskilled)	wages
Capital	man-made resource	AC, TV, mobile phone — everything made by man	interest
Entrepreneur	owner & risk-taker	starts the business; combines land + labour + capital	profit (reward)

Common mistakes / MCQ traps:

Land is not only soil — all natural resources are land.
“Capital” here = man-made resource, not the accounting term (capital employed).
Entrepreneur has NO cost — only a reward (profit). MCQs love to ask “cost of entrepreneur”.

Wages vs salary: wages = weekly / daily (unskilled workers) · salary = monthly (e.g. qualified CA / ACCA).

Entrepreneur takes the risk — could make a loss or a profit — so profit is the reward for that risk.

5. Production Possibility Curve (PPC)

Sir said: everything before this is for MCQs — from here on is the important part. Full attention!

Definition: A PPC shows the different combinations of outputs of two goods that an economy CAN produce with its given resources.

CAN vs IS: “can produce” = potential (able to) · “is producing” = actual (really doing).

“Production possible” = combinations that are possible for me to produce — not necessarily what I am producing.

① How to draw it

Draw two axes first.
Label the vertical axis: capital goods quantity, horizontal axis: consumer goods quantity.
Draw the curve (concave) and mark points.

Why quantity on BOTH axes? — PPC shows combinations of two goods; output = quantity. (e.g. 17 units of capital goods + 10 of consumer goods is one combination.) Always write quantity on both axes.

Why concave? As you increase consumer goods, capital goods automatically decrease — because of opportunity cost. (Only way to avoid OC: buy all of one good.)

on curve = potential · inside = actual · outside = unattainable

② The three kinds of point

Where	Called	What it means
ON the curve (A–E)	POTENTIAL	what the economy can do · efficient allocation (neither over nor under) ⇒ no wastage ⇒ jobs created ⇒ full employment
INSIDE the curve (F)	ACTUAL	the current situation · under-allocation of resources ⇒ wastage ⇒ no jobs ⇒ unemployment
OUTSIDE the curve (G)	UNATTAINABLE	cannot be achieved — scarcity (not enough resources)

Sir’s examples:

Country with coal, gas, minerals, gold but not extracting them = under-allocation ⇒ wastage ⇒ unemployment ⇒ operating at actual. Sir’s picks: UAE, Japan, China, Italy ≈ near potential; Pakistan, Bangladesh ≈ actual.

Memory trick (sir’s analogy): Potential = what you can do · Actual = your current situation · Unattainable = your dream, beyond your means. You can work on or inside the curve, never outside.

6. Changes in Potential — Cases 1 & 2

Always: draw two axes → label → draw the initial PPC → then show the change.

The diagrams — Case 1 (left) & Case 2 (right)

Case 1 — outward shift AB → CD

Case 2 — inward shift AB → CD

Case 1: Potential INCREASES

potential ↑ ⇒ PPC shifts RIGHT (AB → CD)
⇒ productive capacity ↑ ⇒ output & GDP ↑
⇒ economic growth (= potential economic growth)

It is called potential economic growth because the growth came from an increase in potential.

Reasons — 7 each way (any ONE is enough in an answer)

Potential ↑ (shift right)	Potential ↓ (shift left)
1. Discovery of natural resources (oil, gas…)	1. Depletion of natural resources (they run out)
2. Fall in price of energy	2. Rise in price of energy
3. Technological advancement	3. No technological advancement
4. Immigration of workers (I = import)	4. Emigration of workers (E = export)
5. Increase in labour productivity (training)	5. Fall in labour productivity
6. Increase in population	6. Fall in population
7. Increase in quantity of capital goods	7. Decrease in quantity of capital goods

Trick: “I” immigration = Import of workers (I in C+I+G+X−M). “E” = Export of workers leaving.

Energy: cheap energy (cheap electricity & labour) makes big brands outsource production there ⇒ higher potential.
Immigration: bringing in a skilled / well-educated person from abroad raises potential.
Labour productivity: train labour ⇒ more productive ⇒ potential ↑.
Population: more people ⇒ more chance of scientists, doctors, innovators.

Technology example (same one hour):

Before: 100 capital + 200 consumer = 300 units
After new machines: 300 capital + 600 consumer = 900 units
⇒ productive capacity 300 → 900 ⇒ output & GDP ↑ ⇒ economic growth.

Write like this in the exam (Case 1):

“This diagram shows an increase in potential of the economy due to immigration of workers, which will cause a rightward shift in PPC from AB to CD, which will increase the productive capacity of the economy, which will increase output and GDP, resulting in economic growth (potential economic growth).”

Case 2: Potential DECREASES

potential ↓ ⇒ PPC shifts LEFT (AB → CD)
⇒ productive capacity ↓ ⇒ output & GDP ↓
⇒ negative economic growth

Write like this (Case 2):

“This diagram shows a decrease in potential of the economy due to depletion of natural resources, which will cause a leftward shift in PPC from AB to CD, which will reduce the productive capacity of the economy, which will reduce output and GDP, resulting in negative economic growth.”

Sir’s real-life contrast: a country can have many of the “fall” reasons together — expensive energy, low labour productivity, untapped resources, no new technology, skilled people emigrating ⇒ potential keeps falling. A country with new discoveries, cheap energy, new technology, imported workers, trained labour and more capital goods ⇒ potential keeps rising.

7. Changes in Actual — Cases 3 & 4

Same start: two axes, labels, a PPC with points A–D on the curve (potential) and E inside (actual).

The diagrams — Case 3 (left) & Case 4 (right)

Case 3 — E moves TOWARD the curve

Case 4 — E moves TOWARD the origin

Case 3: Actual INCREASES

Actual ↑ ⇒ point E moves toward the PPC / potential. At E there was already under-allocation, wastage and unemployment, so as E moves up:

resources allocated efficiently (resources get extracted)
⇒ wastage ↓ ⇒ jobs created ⇒ unemployment ↓

What makes actual rise? — Aggregate Demand

AD = C + I + G + X − M

Where: C = consumption · I = investment · G = government expenditure · X = exports · M = imports

Actual ↑ (Case 3) — any ONE	Actual ↓ (Case 4) — any ONE
↑ consumption expenditure	↓ consumption
↑ investment expenditure	↓ investment
↑ government expenditure	↓ government expenditure
↑ export revenue	↓ exports
↓ import expenditure	↑ imports

Note: Sir: if you have not studied macro (school students already have), just learn this by heart for now — it “clicks” automatically when macro starts in January.

Multiplier idea (sir’s example):

Investment ↑ by Rs 100 ⇒ production ↑ ⇒ jobs created ⇒ income ↑ ⇒ people consume more ⇒ demand ↑ ⇒ producers make even more output.
⇒ income, output and employment all ↑ (multiplier effect).

Short run vs long run: Short run — increase in actual is beneficial (income, output, employment ↑). Long run — actual keeps rising until it hits potential ⇒ resources become scarce ⇒ prices ↑ ⇒ hyperinflation (sir’s definition: only prices rise, real income stays constant).

Write like this (Case 3):

“This diagram shows an increase in actual due to an increase in consumption / investment / government expenditure, which improves the current situation of the economy — efficient allocation of resources, resulting in lower wastage and lower unemployment. This is beneficial in the short run as income, output and employment increase, but in the long run it will result in hyperinflation where only prices rise and real income is constant.”

Case 4: Actual DECREASES

Point E moves toward the origin (away from the curve).
Under-allocation of resources ↑ ⇒ wastage ↑ ⇒ unemployment ↑.
Economy is heading into recession.
Causes: ↓C, ↓I, ↓G, ↓X, ↑M (any one).

Write like this (Case 4):

“Actual is decreasing, so the point moves towards the origin; under-allocation and wastage increase and unemployment rises, so the economy goes into recession — due to a fall in consumption, investment, government expenditure, exports, or more imports.”

★ MCQ Rule: a change in potential ⇒ the PPC shifts. A change in actual ⇒ the point moves (toward / away from the curve) — the curve itself does not shift.
(Sir said “movement along the curve” — in the diagram it is point E moving; that is the idea to remember.)

★ 8-mark essay: actual vs potential economic growth

“Analyse using a PPC diagram, explain the difference between actual economic growth and potential economic growth.” — how to earn the marks:

① define economic growth ② define PPC + intro diagram → knowledge marks
③ potential growth: what is it · reason · diagram · explanation
④ actual growth: diagram · explanation
⑤ conclusion: potential growth = long run · actual growth = short run

	Potential growth	Actual growth
What moves	the PPC itself shifts outward	point E moves toward the PPC
Cause	7 reasons (resources, energy, tech, workers, productivity, population, capital goods)	↑C, ↑I, ↑G, ↑X or ↓M
Effect	productive capacity ↑ ⇒ output & GDP ↑	less wastage & unemployment; income, output, employment ↑
Time	long run	short run

8. PPC and Opportunity Cost — Cases 5 to 8

Case 5: PPC with opportunity cost (numbers)

Economy’s potential: it can make 200 capital goods or 100 consumer goods. But it chooses point A and produces 140 capital + 30 consumer.

sir’s numbers — sketch, not to scale

what you give up = max − what you make

OC of 140 capital goodsmax consumer = 100producing 30 consumer100 − 30 = 70 C

OC of 30 consumer goodsmax capital = 200producing 140 capital200 − 140 = 60 K

Say it like this: “The opportunity cost of producing 140 units of capital goods is 70 units of consumer goods.” and “…of producing 30 units of consumer goods is 60 units of capital goods.” (Sir’s method: compare with the maximum of the other good. Also an O-level MCQ favourite.)

Rule of thumb: what you forgo / waste / give up = your opportunity cost.

Now the upgrade: three types of opportunity cost — read the SHAPE of the PPC. In an MCQ you can tell the type just by looking at the shape!

CONCAVE: same step in X, bigger and bigger loss ⇒ OC increasing

STRAIGHT: same step in X, same loss ⇒ OC constant

CONVEX: same step in X, smaller and smaller loss ⇒ OC decreasing

Case	Opportunity cost	PPC shape	Also called
6	INCREASING	CONCAVE (normal PPC)	outward-bending PPC
7	CONSTANT	STRAIGHT line (downward sloping)	straight-line PPC
8	DECREASING	CONVEX (like a rectangular hyperbola)	inward-bending PPC

Trick: Concave · Straight · Convex = Increasing · Constant · Decreasing.

Case 6: INCREASING opportunity cost (concave)

Example: government chooses between public goods (e.g. street lights) and subsidy. It cannot have all of both — something is foregone. Move from A: more public goods, less subsidy.

As government provides more public goods and cuts subsidy, the OC rises — each extra unit costs more and more of the other good:

no subsidy ⇒ industries decline ⇒ unemployment ↑
⇒ tax revenue ↓ ⇒ govt expenditure & investment ↓
⇒ standard of living ↓, crime ↑ ⇒ very big loss for the economy

Write like this (Case 6):

“This diagram shows increasing opportunity cost. If the government provides more public goods and less subsidy, opportunity cost increases as this results in higher unemployment, lower tax revenue and a fall in investment and government expenditure.”

Case 7: CONSTANT opportunity cost (straight line)

Label axes: Good Y (vertical) and Good X (horizontal). Move from combination A to B: units of X gained = units of Y lost — each extra unit costs the same.

Straight line ⇒ constant opportunity cost. (Very easy case.)

Case 8: DECREASING opportunity cost (convex)

Flip the concave PPC the other way — like the rectangular hyperbola of unitary elastic demand. Axes: capital goods (vertical), consumer goods (horizontal). Moving from A to B: consumer goods ↑ a lot, capital goods ↓ only a little ⇒ the cost shrinks.

Example: government gives subsidy instead of public goods ⇒ opportunity cost still exists, but smaller, as fewer people are unemployed (the reverse of Case 6).

Note on sir’s wording: in Case 8 sir also said “less tax revenue / lower government expenditure”, which clashes with “less unemployment”. Safest in an answer: write it as the reverse of Case 6 — lower unemployment, higher tax revenue, higher investment & government spending.

★ Homework (sir solves it on Wednesday)

Question (past paper, 8 marks): “Analysing a PPC curve, distinguish between different levels of opportunity cost which an economy will face.”

plan: define PPC & opportunity cost → ① increasing OC (concave) diagram + explain
→ ② constant OC (straight) diagram + explain → ③ decreasing OC (convex) diagram + explain → conclusion

✓ Quick Recap — Whole Chapter Cheat-Sheet

Basic problem: wants unlimited, resources limited ⇒ scarcity ⇒ choice ⇒ opportunity cost = next best alternative foregone.
3 agents: consumer (limited income), producer (limited capital), government (limited funds). 3 questions: what / how / for whom to produce.
FOPs: land (natural) – rent · labour (human) – wages · capital (man-made) – interest · entrepreneur (owner & risk-taker) – profit; entrepreneur has no cost.
PPC: combinations of two goods an economy can produce; capital goods (vertical), consumer goods (horizontal), quantity on both.
On = potential (efficient, no wastage, full employment) · inside = actual (under-allocation, wastage, unemployment) · outside = unattainable (scarcity).
Potential ↑ ⇒ shift right ⇒ capacity ↑ ⇒ output & GDP ↑ ⇒ growth · Potential ↓ ⇒ shift left ⇒ negative growth. 7 reasons each way.
Actual ↑ (↑C ↑I ↑G ↑X ↓M) ⇒ point moves toward PPC ⇒ wastage & unemployment ↓, short-run benefit, long-run hyperinflation · Actual ↓ ⇒ toward origin ⇒ recession.
Potential = shift (long run) · Actual = movement of the point (short run).
OC types: concave = increasing · straight = constant · convex = decreasing.
Case 5 numbers: OC of 140 K = 70 C (100 − 30) · OC of 30 C = 60 K (200 − 140).