Supply

— Economics · O Level —

★ Exam Tip: O Level asks “Define factors of production” — learn it word for word (section 5). Sir also made the class read the movement vs shift paragraph — it is the heart of this chapter (section 8). Chapters done so far: Demand, PED, YED, XED and now Supply; PES comes next.

Covers 2 lectures: ① supply, law of supply, supply curve, invisible hand, factors of production · ② factors affecting supply (other than price), market supply, change in quantity supplied vs change in supply.

1. What is Supply?

Definition: Supply represents the willingness and ability of the producer to produce or sell a good or service.

Link: Demand = willingness + ability (buyer side). Supply = same two words, but the producer’s side.

Who supplies? → the producer. So everything in this chapter is seen from the producer’s point of view.

2. Law of Supply

Supply is done by the producer ⇒ the law of supply is also from the producer’s perspective.

Producer’s one aim = maximise total revenue (we saw this in the usefulness of PED, YED, XED).

Law of SupplyPrice ↑ ⇒ Quantity supplied ↑
Price ↓ ⇒ Quantity supplied ↓

Why? Higher price ⇒ higher revenue ⇒ “I will supply more”.
Lower price ⇒ lower revenue ⇒ “I will supply less”.
So price and quantity supplied have a positive relationship.

Sir’s rule (from day 1): a diagram is always drawn by looking at the relationship. Positive relationship ⇒ upward sloping curve. That is exactly why the supply curve slopes upward.

3. Supply Curve & Movement Along It

Drawing the diagram (do it in this order)

Draw two axes.
Label: P (price) on the vertical axis, Q (quantity supplied) on the horizontal axis.
Draw an upward-sloping supply curve S (price & Qs are positively related).
Take the initial price P → where it touches S is point A → drop down to the axis = Q.
Raise price to P₁ → touches S at B → quantity Q₁.
Lower price to P₂ → touches S at C → quantity Q₂.

price ↑ ⇒ A → B (extension) · price ↓ ⇒ A → C (contraction) — same curve, we only slide along it

Explanation written under the diagram (model answer):

An increase in price from P to P₁ will extend quantity supplied from Q to Q₁, causing movement from point A to point B.
A decrease in price from P to P₂ will contract quantity supplied from Q to Q₂, causing movement from point A to point C.
Moreover, this diagram shows a positive relationship between price and quantity supplied.

Word rule: talking about price → say increase / decrease. Talking about quantity → say extend / contract (sir’s wording rule for explanations). Price changes ⇒ contraction & extension ⇒ shown by movement along the curve.

Ceteris paribus: whenever we talk about price, all other factors are assumed constant. (Sir: “remember this concept — it has a name!”)

4. The Invisible Hand (Demand)

In the diagram we only see price going up or down. But why did price change? There is something hidden behind it:

“There is an invisible hand involved in this diagram, known as demand.”
(the demand curve is the invisible force behind every price change)

the price rise/fall in the supply diagram is really caused by demand

Demand ↑ ⇒ shortage ⇒ price rises on its own ⇒ producer extends quantity supplied (law of supply).
Demand ↓ ⇒ surplus ⇒ price falls on its own ⇒ producer contracts quantity supplied.

✓ Quick Recap — What price does to supply

Price changes cause contraction and extension of quantity supplied.
This is shown by movement along the supply curve.
While talking about price, other factors are constant.
The reason behind the price change = demand (invisible hand).

5. Factors of Production

To produce anything (a pen, a phone) a producer needs resources. Resources are called factors of production.

Definition (O Level):Factors of production are resources which are used to produce a good or service.

There are 4 factors of production. Sir’s table headings: Name · Example · Cost · Reward.

Factor	What it is / examples	Cost (paid as)	Reward
① Land	a natural resource — farm land, oil, river, lake, sea	Rent	—
② Labour	a human resource — skilled (educated, gets salary) & unskilled (maid, labourer)	Wages	—
③ Capital	a man-made resource — machinery	Interest	—
④ Entrepreneur	owner & risk taker who combines land + labour + capital	— (none)	Profit

Common mistake: students think land = only ground. NO — every natural resource comes in the category of land (oil, river, lake, sea…). Sir stressed this strongly.

Example — making a phone:

I need a place → land; people to work → labour; machines → capital. When I combine these three and decide to start making phones I am the risk taker (what if I make a loss, what if the phone doesn’t sell?) = the entrepreneur, and my reward is profit.

Trick: 3 factors have a cost (rent, wages, interest) — only 1 has a reward (entrepreneur → profit). Entrepreneur’s money put in is “investment”, but he gets a return, so it is not a cost.

Note: rent is a reward for the landowner, but for the producer who hires the land it is a cost. It only becomes the producer’s reward if he owns land and lets it out to someone else.

6. Factors Affecting Supply (other than price)

Factors affecting supply = other factors = non-price factors (everything that is other than price).
When we talk about other factors, price is assumed constant.
Same heading as in the demand chapter — there it was “factors affecting demand other than price”.

Price vs other factorsPrice changes ⇒ movement along the curve (last class)
Other factors change ⇒ the curve shifts (today)

Supply increases ⇒ curve shifts rightward.
Supply decreases ⇒ curve shifts leftward.
Rule for every chapter: anything increases → right shift; anything decreases → left shift.
Demand had 6 factors (income, direct tax, related goods, advertisement, population, taste/pattern). Supply has only 4.

Diagram: shift of the supply curve

Axes → label P, Q → draw price as a constant line (because we are talking about other factors) → draw upward S → where S touches the price line, drop down to Q.

S → S₁ (right) : more supply at the SAME price · S → S₂ (left) : less supply at the same price

Why S → S₁ (right)? fall in cost of production, removal of indirect tax, subsidy by government, technological advancement.
Why S → S₂ (left)? increase in cost of production, removal of subsidy, imposition of indirect tax.

① Cost of production

Producing needs resources (factors of production) ⇒ cost of production = cost of the resources = cost of FoPs. Entrepreneur is not included (he gets a reward, not a cost).

Land → rent
Labour → wages
Capital → interest

Example:

I hire skilled labour ⇒ skilled labour is expensive, demands higher wages ⇒ my cost goes up.

“Kharcha badh raha hai” — profit shrinking day by day, so he slowly cuts supply

Cost of production ↑ ⇒ supply ↓. Cost of production ↓ ⇒ supply ↑.
So cost of production is the factor that can make supply increase OR decrease.

Sir’s tuition-centre example:

My tuition centre fills up — 50 students on day 1 (group A full). The landlord (tenant-owner) sees it, gets greedy and raises my rent ⇒ my cost ↑ ⇒ my burden ↑. I will not bear it myself — I pass it on to the consumer as a higher price (I raise the tuition fee). That is the whole chain behind a price rise.

Next-chapter preview: supply ↓ ⇒ shortage ⇒ price ↑ ⇒ quantity demanded ↓, and by what % it falls is told by PED. (Sir builds the basics of the next chapter now.)

② Technological advancement

Two types of production: capital intensive = more machines, less labour · labour intensive = more labour, fewer machines.

Technological advancement meansthe business is adopting capital-intensive production methods (using machines more, labour less).

machines make more goods (productivity) and fewer mistakes (efficiency)

More machines ⇒ more goods than before ⇒ productivity ↑; machines also make fewer mistakes ⇒ efficiency ↑.
Efficiency ↑ ⇒ wastage ↓ ⇒ cost of making the product ↓ ⇒ burden ↓ ⇒ producer is motivated ⇒ supply ↑.
Then: supply ↑ ⇒ surplus ⇒ price ↓ ⇒ quantity demanded ↑ (size by PED).

Remember: technological advancement can only increase supply — never decrease it. (Cost of production can do both.)

③ Indirect tax

DefinitionIndirect tax is a tax that is levied on goods and services.

In Pakistan it comes as GST (general sales tax); in other countries as VAT (value added tax).
Water bottle: label shows retail price Rs 28 and a Rs 5 sales tax (ST = sales tax = GST).
Restaurants (Pakistan, as sir said): pay cash ⇒ 17% charged above your bill; pay by card ⇒ 8%. That 8%/17% is GST. Gulf students know the same thing as VAT.
VAT reclaim counter at airports (UAE etc.): tourists show their slips on exit and get VAT back, because they earned in Pakistan but spent in someone else’s country.
Pencil: Rs 100 + 10% GST = Rs 110. Value of the pencil got an addition ⇒ that is why it is called value added tax.

producer passes the tax burden to the consumer as a higher price

Indirect tax is the factor that makes supply decrease (when imposed / increased).
Removal of indirect tax ⇒ cost ↓ ⇒ producer motivated ⇒ supply ↑.
Producer won’t bear the tax himself — he “passes it to the consumer in the form of higher prices”.

Don’t mix up: direct tax (on income) was a factor of demand (last chapter). Indirect tax (on goods & services) is a factor of supply.

Note: in the recording sir slipped once and said “cost will fall” when tax is imposed — he meant (and the rest of the lecture says) cost rises.

④ Subsidy

DefinitionA subsidy is a grant or cash payment that the government gives to the producer, for the benefit of the consumer.

Why? When there is inflation / high prices in the country, the government helps producers so that their cost falls and prices stay low for consumers.

subsidy ⇒ cheaper production ⇒ more supply ⇒ lower price

Subsidy ⇒ supply ↑ (right shift). Removal of subsidy ⇒ supply ↓ (left shift).

Extra (sir’s quick question): bad weather / bad harvest ⇒ supply ↓. Not one of the 4 main factors, but it reduces supply just the same.

Summary of the 4 factors

Factor	What happens	Supply	Shift
Cost of production	cost ↑ \| cost ↓	↓ \| ↑	left \| right
Indirect tax	imposed \| removed	↓ \| ↑	left \| right
Subsidy	given \| removed	↑ \| ↓	right \| left
Technological advancement	improves	↑ only	right
Bad weather / bad harvest	occurs	↓	left

Sir’s rapid-fire check: removal of indirect tax → supply ↑ · removal of subsidy → supply ↓ · fall in cost of production → supply ↑ · technology → only ↑ · bad weather/harvest → supply ↓. Today’s class agenda was exactly this: which factor makes supply rise, which makes it fall.

7. Market Supply

Individual supply = what one firm supplies. Market supply = what all firms together supply.

DefinitionMarket supply is the horizontal summation of all individual supply curves.
It is calculated by adding the supply of all individual firms.

at the same price add the quantities sideways (horizontally) ⇒ market curve

Example 1 — airlines:

Emirates supplies 100 flights/month, Qatar Airways 120 flights/month ⇒ market supply = 100 + 120 = 220 flights/month.

Example 2 — class:

21 students, each supplies 100 units ⇒ 21 × 100 = 2100 units = market (total) supply.

Note: in the recording sir once said “200” for Qatar by slip, then corrected the total to 220 (100 + 120).

8. Change in Quantity Supplied vs Change in Supply

Recall the law of supply: price ↑ ⇒ Qs ↑ (more revenue); price ↓ ⇒ Qs ↓ (less revenue). So a change in quantity supplied happens because of a change in price.

	Change in QUANTITY SUPPLIED	Change in SUPPLY
Caused by	change in the price of the good	change in other (non-price) factors
Assumed constant	all other factors	price
Words used	extension / contraction	increase / decrease
On the diagram	movement along the same supply curve	shift of the whole curve (right ↑ / left ↓)
Reasons	higher price ⇒ higher revenue (law of supply)	cost of production, indirect tax, subsidy, technological advancement

price changes ⇒ MOVEMENT (A → B, A → C)

other factors ⇒ SHIFT (S → S₁ or S₂)

⭐ Paragraph sir made the class read — learn it:Changes in quantity supplied will be due to changes in price, keeping all other factors constant, and cause movement along the supply curve, while changes in supply are due to changes in other factors, keeping price constant, and cause a shift in the supply curve.

9. Full Chapter Cheat-Sheet

✓ Supply — everything on one page

Supply = willingness + ability of the producer to produce or sell a good/service.
Law of supply: price ↑ ⇒ Qs ↑, price ↓ ⇒ Qs ↓ (higher price ⇒ higher revenue). Positive relation ⇒ upward sloping curve.
Price change ⇒ extension / contraction ⇒ movement along curve (A → B / A → C); other factors constant (ceteris paribus).
Invisible hand behind price = demand: demand ↑ ⇒ shortage ⇒ price ↑; demand ↓ ⇒ surplus ⇒ price ↓.
Factors of production = resources used to produce a good/service: Land (natural → rent), Labour (human → wages), Capital (man-made → interest), Entrepreneur (owner & risk taker, combines the 3 → profit = reward).
Land = every natural resource (oil, river, lake, sea), not only ground.
Other factors (non-price) ⇒ price constant ⇒ shift: supply ↑ → right, supply ↓ → left.
4 factors: cost of production (↑ or ↓ supply) · indirect tax (imposed ⇒ ↓, removed ⇒ ↑) · subsidy (given ⇒ ↑, removed ⇒ ↓) · technological advancement (only ↑). Bad weather / harvest ⇒ ↓.
Chain for ↓: cost/tax ↑ ⇒ burden ↑ ⇒ demotivated ⇒ supply ↓ ⇒ shortage ⇒ price ↑ ⇒ Qd ↓ (size = PED). Chain for ↑ is the mirror image (surplus ⇒ price ↓ ⇒ Qd ↑).
Technological advancement = capital-intensive methods ⇒ productivity ↑, efficiency ↑, wastage ↓, cost ↓.
Indirect tax = tax on goods & services (GST in Pakistan, VAT abroad); subsidy = grant/cash payment from govt to producer for the consumer’s benefit.
Market supply = horizontal sum of all firms’ supply (e.g. 100 + 120 = 220 flights).
Change in Qs ← price (movement) · Change in supply ← other factors (shift).
Next class: PES — price elasticity of supply.