Theory of Price Determination

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8.1 Meaning of Price Determination

Price determination refers to the process by which the market sets the price of a good or service based on the interaction of demand and supply forces.

  • Equilibrium Price (Pe): This is the price at which the quantity demanded equals the quantity supplied. At this point, there is neither shortage nor surplus in the market.
  • Equilibrium Quantity (Qe): The amount of goods that consumers are willing to buy and producers are willing to sell at the equilibrium price.

Example: If yam sellers in Mile 12 market supply 500 tubers at ₦2,000 each, and buyers are also willing to purchase 500 tubers at that price, then ₦2,000 is the equilibrium price and 500 tubers is the equilibrium quantity.

8.2 The Demand and Supply Curves

  • Demand Curve: A graphical representation of the law of demand. It slopes downward from left to right, showing that as price falls, quantity demanded increases.
  • Supply Curve: A graphical representation of the law of supply. It slopes upward from left to right, showing that as price rises, quantity supplied increases.
  • Intersection Point: The point where the two curves meet represents the equilibrium price and quantity.

Example: In Lagos markets, if the price of rice increases, more traders will supply rice (to make profits), but fewer consumers will demand it. The price stabilizes where supply equals demand.

8.3 Market Disequilibrium

When price is not at equilibrium, two conditions may occur:

  1. Excess Demand (Shortage):
    • Occurs when price is below equilibrium.
    • Quantity demanded > Quantity supplied.
    • Results in long queues, black markets, or rationing.
    • Example: During fuel scarcity in Nigeria, when the government fixes pump price below the market equilibrium, demand exceeds supply, leading to scarcity.
  2. Excess Supply (Surplus):
    • Occurs when price is above equilibrium.
    • Quantity supplied > Quantity demanded.
    • Results in unsold goods, wastage, or a fall in producer revenue.
    • Example: If too many farmers bring tomatoes to the market during harvest season, prices crash because supply exceeds demand.

In both cases, natural market forces push price back to equilibrium unless government intervenes.

8.4 Shifts in Demand and Supply

The equilibrium price and quantity are not fixed; they change when demand or supply shifts.

  • Increase in Demand: Shifts demand curve rightward → higher equilibrium price and quantity.
    Example: During festive periods (e.g., Christmas), demand for rice increases, pushing up both price and sales volume.
  • Decrease in Demand: Shifts demand curve leftward → lower equilibrium price and quantity.
    Example: If people switch from garri to rice due to lifestyle changes, demand for garri falls, causing its price to drop.
  • Increase in Supply: Shifts supply curve rightward → lower equilibrium price but higher quantity.
    Example: Government fertilizer subsidies may increase maize production, leading to lower maize prices but more availability.
  • Decrease in Supply: Shifts supply curve leftward → higher equilibrium price but lower quantity.
    Example: Flooding in northern Nigeria reduces tomato output, pushing up tomato prices in Lagos markets.

8.5 Price Controls by Government

Sometimes, governments interfere in the natural working of demand and supply.

  1. Price Ceiling (Maximum Price):
    • Set below equilibrium price to make goods affordable.
    • Leads to shortages if not backed by increased supply.
    • Example: Nigerian government fixing petrol price below market level often leads to fuel scarcity.
  2. Price Floor (Minimum Price):
    • Set above equilibrium price to protect producers.
    • Leads to surpluses if not backed by guaranteed purchases.
    • Example: Government fixing cocoa prices higher than the market price to encourage farmers may cause unsold stock unless government buys the excess.

8.6 Importance of the Price Mechanism

The price system is like an invisible hand that regulates the economy. It:

  • Allocates resources: Producers shift resources into profitable goods.
  • Rations goods: Scarce goods are allocated to those willing and able to pay.
  • Transmits information: A rise in price signals scarcity to consumers and profitability to producers.
  • Encourages efficiency: Firms must reduce costs to remain competitive at prevailing market prices.
  • Balances demand and supply: Prevents prolonged shortages or surpluses unless external interference occurs.

Example: In Nigeria, if chicken prices rise, more poultry farmers will enter the business, balancing demand and supply.

8.7 Key Points to Master for WAEC Exams

  1. Equilibrium Price & Quantity:
    • Meaning, determination, and graphical illustration.
  2. Disequilibrium:
    • Concepts of excess demand and excess supply with real-life examples.
  3. Shifts in Demand & Supply:
    • How changes in consumer preferences, incomes, and technology affect equilibrium.
  4. Price Controls:
    • Distinction between price ceiling and price floor with Nigerian examples.
  5. Price Mechanism:
    • Its roles in allocation, rationing, information, efficiency, and balance.
  6. Graphical Analysis:
    • Students must master drawing demand and supply curves, showing equilibrium, shortages, and surpluses.

Section A: 30 Objective Questions (WAEC Style)

Instruction: Choose the option that best answers each of the following questions.

  1. Price is determined in a free market by the interaction of
    A. producers and wholesalers
    B. supply and demand
    C. retailers and consumers
    D. government and consumers
  2. The equilibrium price is the price at which
    A. supply is greater than demand
    B. demand equals supply
    C. demand exceeds supply
    D. producers maximize profit
  3. If the price of a good is fixed above equilibrium, the likely result is
    A. shortage
    B. equilibrium
    C. surplus
    D. rationing
  4. When quantity demanded is greater than quantity supplied, the market experiences
    A. equilibrium
    B. surplus
    C. shortage
    D. efficiency
  5. The point where the demand and supply curves intersect is called
    A. market equilibrium
    B. price control
    C. disequilibrium
    D. price ceiling
  6. A maximum price fixed by government below equilibrium is known as
    A. price floor
    B. price ceiling
    C. equilibrium price
    D. market price
  7. A price floor set above equilibrium price will result in
    A. shortage
    B. equilibrium
    C. surplus
    D. higher demand
  8. When demand increases while supply remains constant, the equilibrium price will
    A. fall and quantity decrease
    B. rise and quantity increase
    C. remain unchanged
    D. fall and quantity increase
  9. If supply decreases while demand remains unchanged, equilibrium price will
    A. rise while quantity falls
    B. fall while quantity rises
    C. rise while quantity rises
    D. fall while quantity falls
  10. Which of the following is NOT a function of the price mechanism?
    A. Allocation of resources
    B. Encouragement of efficiency
    C. Equitable distribution of income
    D. Transmission of information
  11. A shortage in the market implies that
    A. price is below equilibrium
    B. supply is greater than demand
    C. equilibrium has been attained
    D. sellers cannot sell their goods
  12. A surplus occurs when
    A. demand equals supply
    B. supply is greater than demand
    C. demand is greater than supply
    D. price is at equilibrium
  13. Government intervention in price determination is often to
    A. ensure producers make profit
    B. stabilize the market
    C. reduce consumer sovereignty
    D. eliminate demand
  14. Which of these situations best describes disequilibrium?
    A. Price where demand equals supply
    B. Price where demand is not equal to supply
    C. Market forces of demand and supply working freely
    D. Price ceiling adjusted to equilibrium
  15. An increase in supply while demand remains constant leads to
    A. higher price, lower quantity
    B. lower price, higher quantity
    C. lower price, lower quantity
    D. higher price, higher quantity
  16. A decrease in demand while supply is constant results in
    A. higher equilibrium price and quantity
    B. lower equilibrium price and quantity
    C. higher price, lower quantity
    D. lower price, higher quantity
  17. The fixing of minimum wage by government is an example of
    A. price ceiling
    B. price floor
    C. price mechanism
    D. equilibrium price
  18. Black markets often arise when
    A. government fixes maximum prices
    B. producers fix prices
    C. prices are left to market forces
    D. supply exceeds demand
  19. If demand decreases and supply decreases simultaneously, equilibrium price will
    A. definitely rise
    B. definitely fall
    C. may rise or fall depending on the extent of change
    D. remain unchanged
  20. When excess supply exists, producers will usually
    A. increase price
    B. reduce price
    C. maintain price
    D. stop production
  21. If the price of garri is kept below equilibrium by government, the likely effect is
    A. surplus of garri
    B. shortage of garri
    C. equilibrium in garri market
    D. wastage of garri
  22. The role of prices in signaling scarcity of goods is called
    A. rationing function
    B. allocative function
    C. informational function
    D. distributive function
  23. One major disadvantage of a price floor is
    A. creation of shortage
    B. creation of surplus
    C. reduction of producer income
    D. reduction of cost of production
  24. If the government buys up surplus caused by price floor, this is called
    A. buffer stock scheme
    B. rationing
    C. monopoly pricing
    D. subsidy removal
  25. The law of supply states that
    A. the lower the price, the higher the quantity supplied
    B. the higher the price, the lower the supply
    C. the higher the price, the higher the quantity supplied
    D. supply is independent of price
  26. Which of the following is a consequence of fixing price ceiling below equilibrium?
    A. Surplus goods
    B. Shortage of goods
    C. Wastage of goods
    D. Producer monopoly
  27. The equilibrium point is reached when
    A. buyers want to buy less than sellers want to sell
    B. buyers want to buy more than sellers want to sell
    C. buyers want to buy exactly what sellers want to sell
    D. government fixes the price
  28. If both demand and supply increase simultaneously, equilibrium quantity will
    A. increase
    B. decrease
    C. remain constant
    D. fluctuate
  29. Price determination is best explained by
    A. Keynesian theory
    B. Demand and supply theory
    C. Utility theory
    D. Cost-push theory
  30. In a perfectly competitive market, the main determinant of price is
    A. government policy
    B. demand and supply
    C. producer monopoly
    D. consumer welfare

 

Section B: Essay Questions (15 WAEC-style)

Instruction: Answer any number of questions as directed by your teacher or examiner.

Question 1

(a) Explain the concept of equilibrium price and equilibrium quantity.
(b) With the aid of a well-labelled diagram, show how equilibrium price is determined in the market.

Question 2

Discuss the effects of fixing price above the equilibrium level in a free market economy.

Question 3

(a) What is excess demand?
(b) Explain, with the aid of a diagram, how excess demand is eliminated in a market economy.

Question 4

Describe four functions of the price mechanism in an economy.

Question 5

Explain five factors that can cause a shift in the demand curve and show how each can affect equilibrium price.

Question 6

(a) Define price ceiling.
(b) Explain three effects of price ceiling on consumers and producers.

Question 7

Explain, with the aid of a diagram, the effect of an increase in supply on equilibrium price and quantity.

Question 8

Discuss four reasons why governments intervene in price determination.

Question 9

(a) What is price floor?
(b) State and explain three consequences of fixing a price floor above equilibrium.

Question 10

Using diagrams, explain how the following affect equilibrium price and quantity:
(i) an increase in demand with constant supply
(ii) a decrease in supply with constant demand

Question 11

Discuss five limitations of the price mechanism as a means of resource allocation in West African economies.

Question 12

(a) Define the term “market disequilibrium.”
(b) Explain two conditions that can lead to market disequilibrium.

Question 13

Explain four advantages and four disadvantages of government price control in an economy.

Question 14

(a) With the aid of a diagram, explain how simultaneous increase in both demand and supply affects equilibrium.
(b) In what ways does the extent of the change in demand and supply influence the final equilibrium?

Question 15

Examine the role of price determination in solving the basic economic problems of what to produce, how to produce, and for whom to produce.

Answers to Objective Questions

  1. B – Price is determined by demand and supply.
  2. B – Equilibrium price occurs when demand = supply.
  3. C – Price above equilibrium → surplus.
  4. C – Demand > supply → shortage.
  5. A – Demand and supply intersect at market equilibrium.
  6. B – Government sets maximum price below equilibrium = price ceiling.
  7. C – Price floor above equilibrium creates surplus.
  8. B – Demand ↑ → price ↑ and quantity ↑.
  9. A – Supply ↓ → price ↑ and quantity ↓.
  10. C – Equitable distribution of income is not a function of price mechanism.
  11. A – Shortage occurs when price < equilibrium.
  12. B – Surplus = supply > demand.
  13. B – Government intervenes to stabilize markets.
  14. B – Disequilibrium = demand ≠ supply.
  15. B – Increase in supply with constant demand lowers price, raises quantity.
  16. B – Decrease in demand with constant supply → price ↓, quantity ↓.
  17. B – Minimum wage = price floor.
  18. A – Black markets appear under maximum price control.
  19. C – Price change depends on relative shifts in demand and supply.
  20. B – To clear surplus, producers lower price.
  21. B – Price ceiling below equilibrium → shortage.
  22. C – Price informs producers/consumers = informational function.
  23. B – Price floor creates surplus.
  24. A – Government buys surplus under buffer stock scheme.
  25. C – Law of supply: higher price → higher supply.
  26. B – Price ceiling below equilibrium causes shortage.
  27. C – Equilibrium when buyers buy exactly what sellers sell.
  28. A – Simultaneous demand and supply increase → quantity rises.
  29. B – Price determination best explained by demand and supply theory.
  30. B – In perfect competition, price is determined by demand and supply.

Model Essay Answers (WAEC Style)

Q1: Equilibrium Price

  • Definition: Price where quantity demanded = quantity supplied.
  • Equilibrium Quantity: The amount bought/sold at equilibrium.
  • Diagram: Downward demand curve, upward supply curve, intersect at Pe and Qe.
  • Explanation: At Pe, market clears (no surplus or shortage).

Q2: Price Above Equilibrium

  • Creates surplus (supply > demand).
  • Producers cannot sell all goods.
  • Prices may be forced down.
  • Leads to inefficiency and wastage.

Q3: Excess Demand

  • Definition: Situation where demand > supply at given price.
  • Diagram: Demand curve above supply at low price.
  • Adjustment: Shortage pushes price up until equilibrium is restored.

Q4: Functions of Price Mechanism

  1. Allocates resources to where demand is high.
  2. Rations scarce goods during shortages.
  3. Provides incentives to producers/consumers.
  4. Transmits information about market conditions.

Q5: Factors Shifting Demand Curve

  1. Change in income.
  2. Change in taste/fashion.
  3. Price of substitutes/complements.
  4. Population size.
  5. Price expectations.
  • Effect: Higher demand shifts curve right → higher Pe and Qe.

Q6: Price Ceiling

  • Definition: Government maximum price below equilibrium.
  • Effects:
    1. Creates shortage.
    2. Encourages black markets.
    3. Consumers benefit from lower prices, but producers lose revenue.

Q7: Increase in Supply

  • Diagram: Supply curve shifts right.
  • Result: Price falls, quantity increases.
  • Explanation: More goods available at same demand level.

Q8: Why Governments Intervene

  1. Protect consumers from high prices.
  2. Stabilize economy.
  3. Protect producers’ income.
  4. Prevent exploitation/monopoly.

Q9: Price Floor

  • Definition: Minimum price above equilibrium.
  • Consequences:
    1. Surplus of goods.
    2. Government may need to buy excess.
    3. Black markets discouraged.

Q10: Effects of Demand/Supply Changes

(i) Demand ↑ (supply constant) → higher Pe, higher Qe.
(ii) Supply ↓ (demand constant) → higher Pe, lower Qe.

  • Diagrams: Demand rightward shift; Supply leftward shift.

Q11: Limitations of Price Mechanism

  1. Ignores income inequality.
  2. Cannot provide public goods.
  3. May cause unemployment.
  4. May worsen economic instability.
  5. Black markets under price controls.

Q12: Market Disequilibrium

  • Definition: Demand ≠ supply at given price.
  • Causes:
    1. Government fixing prices.
    2. Sudden changes in demand/supply.

Q13: Advantages & Disadvantages of Price Control

  • Advantages:
    1. Protects consumers.
    2. Reduces inflation.
    3. Prevents exploitation.
    4. Stabilizes markets.
  • Disadvantages:
    1. Creates shortages/surpluses.
    2. Encourages black markets.
    3. Discourages efficiency.
    4. Burden on government (subsidies).

Q14: Simultaneous Increase in Demand & Supply

  • Diagram: Both curves shift right.
  • Result: Quantity ↑, price may rise/fall depending on relative shifts.
  • Explanation: If demand shift > supply shift → price rises; vice versa.

Q15: Price Determination & Basic Economic Problems

  • What to produce: Goods with high demand.
  • How to produce: Cheapest methods chosen (incentives via prices).
  • For whom to produce: Those able/willing to pay at equilibrium price.

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