Microeconomics Final Exam Practice: Key Concepts and Applications

Perfect Competition

Characteristics of Perfect Competition

Perfect competition is a market structure characterized by many firms selling identical products, with no single firm able to influence the market price. Entry and exit are free, and all participants have perfect information.

• Price Taker: Each firm accepts the market price as given.

• Identical Products: Goods offered by different firms are perfect substitutes.

• Free Entry and Exit: Firms can enter or leave the market without restriction.

• Many Buyers and Sellers: No single buyer or seller can influence the price.

Example: Agricultural markets, such as wheat or corn, often approximate perfect competition.

Profit Maximization in Perfect Competition

Firms maximize profit by producing the quantity where marginal cost (MC) equals marginal revenue (MR), which equals price (P) in perfect competition.

• Profit-Maximizing Rule: Produce where $MC = MR = P$.

• Short-Run Decisions: Firms may earn profits, break even, or incur losses.

• Long-Run Equilibrium: Economic profit is zero due to entry and exit.

Formula:

$\text{Profit} = (P - ATC) \times Q$

Example: If price is above average total cost (ATC), the firm earns a profit.

Marginal Revenue and Marginal Cost Table

Tables are often used to determine the profit-maximizing output by comparing marginal revenue and marginal cost.

Q	MR	MC
1	100	50
2	100	75
3	100	100
4	100	125

Application: The firm should produce up to the quantity where MR = MC (here, Q = 3).

Monopoly

Characteristics of Monopoly

A monopoly is a market with a single seller that controls the entire supply of a unique product with no close substitutes.

• Price Maker: The monopolist can set the price by choosing output level.

• Barriers to Entry: High barriers prevent other firms from entering the market.

• Unique Product: No close substitutes exist.

Example: Local utilities (water, electricity) are often monopolies.

Profit Maximization in Monopoly

The monopolist maximizes profit where marginal revenue equals marginal cost, but price is set above marginal cost.

• Profit-Maximizing Rule: Produce where $MR = MC$, then charge the price on the demand curve at that quantity.

• Economic Profit: Can persist in the long run due to barriers to entry.

Formula:

$\text{Profit} = (P - ATC) \times Q$

Example: If the monopolist's price is above ATC, it earns a profit.

Price Discrimination

Price discrimination occurs when a monopolist charges different prices to different consumers for the same good, not based on cost differences.

• Requirements: Market power, ability to segment markets, and prevent resale.

• Types: First-degree (perfect), second-degree, and third-degree price discrimination.

Example: Airline tickets priced differently based on purchase timing or customer type.

Monopolistic Competition

Characteristics

Monopolistic competition is a market structure with many firms selling differentiated products and free entry and exit.

• Product Differentiation: Each firm offers a product that is slightly different from its competitors.

• Many Sellers: No single firm dominates the market.

• Free Entry and Exit: Firms can enter or leave the market easily.

Example: Restaurants, clothing brands.

Demand Curve

Each firm faces a downward-sloping demand curve, giving it some control over price.

• Short-Run: Firms can earn profits or losses.

• Long-Run: Entry and exit drive economic profit to zero.

Oligopoly and Game Theory

Oligopoly

An oligopoly is a market structure dominated by a few large firms, which may collude or compete.

• Interdependence: Firms' decisions affect each other.

• Barriers to Entry: Significant barriers prevent new firms from entering.

Example: Automobile or airline industries.

Game Theory and the Prisoner's Dilemma

Game theory analyzes strategic interactions among firms. The prisoner's dilemma illustrates why firms may not cooperate even when it is in their best interest.

• Dominant Strategy: The best action for a player regardless of what others do.

• Nash Equilibrium: Each player's strategy is optimal given the strategies of others.

Example: Two firms deciding whether to collude or compete on prices.

International Trade: Tariffs and Quotas

Tariffs

A tariff is a tax on imported goods, raising the domestic price and reducing imports.

• Effects: Increases domestic production, decreases consumption, generates government revenue, and causes deadweight loss.

Graphical Analysis: Tariffs shift the supply curve, raising equilibrium price and reducing quantity imported.

Quotas

A quota is a limit on the quantity of a good that can be imported.

• Effects: Similar to tariffs, but quota rents may go to foreign producers.

Example: Import quotas on sugar or steel.

Opportunity Cost and Comparative Advantage

Comparative advantage is the ability to produce a good at a lower opportunity cost than another producer.

• Opportunity Cost: The value of the next best alternative foregone.

• Specialization: Countries benefit by specializing in goods where they have comparative advantage and trading.

Table Example:

Country	Good X	Good Y
A	10	20
B	30	10

Application: Calculate opportunity cost to determine comparative advantage.

Cost Concepts

Short-Run and Long-Run Costs

Costs are classified as fixed or variable in the short run, while all costs are variable in the long run.

• Average Total Cost (ATC): $ATC = \frac{TC}{Q}$

• Marginal Cost (MC): $MC = \frac{\Delta TC}{\Delta Q}$

• Economies of Scale: Long-run average cost decreases as output increases.

Example: A firm experiences economies of scale if doubling output less than doubles total cost.

Market Supply and Demand

Market Equilibrium

Market equilibrium occurs where quantity demanded equals quantity supplied at the equilibrium price.

• Surplus: Quantity supplied exceeds quantity demanded at a given price.

• Shortage: Quantity demanded exceeds quantity supplied at a given price.

Graphical Representation: The intersection of the supply and demand curves determines equilibrium.

Shifts in Supply and Demand

Changes in non-price determinants shift the supply or demand curve, affecting equilibrium price and quantity.

• Demand Shifters: Income, tastes, prices of related goods, expectations, number of buyers.

• Supply Shifters: Input prices, technology, expectations, number of sellers.

Example: An increase in consumer income shifts the demand curve for normal goods to the right.

Elasticity

Price Elasticity of Demand

Price elasticity of demand measures the responsiveness of quantity demanded to a change in price.

• Formula: $E_d = \frac{\% \Delta Q_d}{\% \Delta P}$

• Elastic: $|E_d| > 1$ (quantity demanded is responsive to price changes)

• Inelastic: $|E_d| < 1$ (quantity demanded is not very responsive)

Example: Luxury goods tend to have more elastic demand than necessities.

Summary Table: Market Structures

Market Structure	# of Firms	Type of Product	Entry Barriers	Price Control
Perfect Competition	Many	Identical	None	None (Price Taker)
Monopoly	One	Unique	High	Significant (Price Maker)
Monopolistic Competition	Many	Differentiated	Low	Some
Oligopoly	Few	Identical or Differentiated	High	Some/Collusive

Additional info:

• Some explanations and examples have been expanded for clarity and completeness.

• Tables and figures referenced in the questions have been recreated or summarized for study purposes.