Midterm 2 Study Guide: Principles of Microeconomics (Chapters 4, 5, 6, 7, 12)

Chapter 4: Demand, Supply, and Equilibrium

The Meaning of Markets

Markets are institutions or arrangements where buyers and sellers interact to exchange goods and services. The behavior of participants determines prices and quantities traded.

• Market: Any mechanism that brings together buyers and sellers.

• Example: The stock market, farmers' markets, and online platforms like Amazon.

How Buyers Behave

Buyers make decisions based on preferences, prices, and available income, aiming to maximize their satisfaction.

• Law of Demand: As the price of a good increases, the quantity demanded decreases, ceteris paribus.

• Demand Schedule: A table showing quantities demanded at different prices.

• Demand Curve: A graphical representation of the demand schedule, typically downward sloping.

• Difference Between Qd and D: Qd (Quantity Demanded) refers to a specific amount at a given price; D (Demand) refers to the entire relationship between price and quantity.

• Individual vs. Market Demand: Individual demand is for one consumer; market demand is the sum of all individual demands.

How Sellers Behave

Sellers decide how much to offer based on costs, technology, and market prices.

• Law of Supply: As the price of a good increases, the quantity supplied increases, ceteris paribus.

• Supply Schedule: A table showing quantities supplied at different prices.

• Supply Curve: A graphical representation of the supply schedule, typically upward sloping.

• Difference Between Qs and S: Qs (Quantity Supplied) is the amount at a specific price; S (Supply) is the entire relationship between price and quantity.

• Individual vs. Market Supply: Individual supply is from one seller; market supply is the sum of all individual supplies.

Market Equilibrium

Market equilibrium occurs where quantity demanded equals quantity supplied, determining the market price and quantity.

• Equilibrium Price: The price at which Qd = Qs.

• Equilibrium Quantity: The quantity traded at equilibrium price.

• Equation: $Q_d = Q_s$

Market Disequilibrium

Disequilibrium occurs when the market price is not at equilibrium, leading to shortages or surpluses.

• Shortage: Qd > Qs; price tends to rise.

• Surplus: Qs > Qd; price tends to fall.

Changes in Market Equilibrium

Shifts in demand or supply curves change equilibrium price and quantity.

• Increase in Demand: Raises equilibrium price and quantity.

• Increase in Supply: Lowers equilibrium price, raises equilibrium quantity.

Chapter 5: Consumers and Incentives

Consumer Surplus

Consumer surplus is the difference between what consumers are willing to pay and what they actually pay.

• Formula: $\text{Consumer Surplus} = \text{Willingness to Pay} - \text{Actual Price}$

• Example: If a consumer is willing to pay $10 for a product but buys it for $7, their surplus is $3.

Demand Elasticities

Elasticity measures how responsive quantity demanded is to changes in price, income, or prices of other goods.

• Price Elasticity of Demand: Measures responsiveness to price changes.

  • Formula: $\text{Price Elasticity} = \frac{\% \text{Change in Quantity Demanded}}{\% \text{Change in Price}}$

• Cross Price Elasticity of Demand: Measures responsiveness to price changes of another good.

  • Formula: $\text{Cross Price Elasticity} = \frac{\% \text{Change in Quantity Demanded of Good A}}{\% \text{Change in Price of Good B}}$

• Income Elasticity of Demand: Measures responsiveness to income changes.

  • Formula: $\text{Income Elasticity} = \frac{\% \text{Change in Quantity Demanded}}{\% \text{Change in Income}}$

Chapter 6: Sellers and Incentives

Seller’s Problem

Sellers aim to maximize profit by choosing the optimal quantity to produce, considering costs and market price.

• Profit: $\text{Profit} = \text{Total Revenue} - \text{Total Cost}$

• Optimum Quantity: Where marginal cost equals marginal revenue.

Law of Diminishing Returns

As more of a variable input is added to a fixed input, the additional output from each new unit eventually decreases.

• Example: Adding more workers to a factory increases output, but after a point, each additional worker contributes less.

Finding Optimum Quantity and Profit/Loss Area on Graph

The optimum quantity is where marginal cost equals marginal revenue. The profit or loss area is the difference between total revenue and total cost.

• Graph: The area between price and average cost curve, multiplied by quantity.

Shutdown or Staying in Business Decisions

Firms decide to shut down or continue based on whether revenue covers variable costs.

• Shutdown Rule: If price < average variable cost, shut down in the short run.

• Stay in Business: If price > average variable cost, continue operating.

Producer Surplus

Producer surplus is the difference between the price sellers receive and the minimum price they are willing to accept.

• Formula: $\text{Producer Surplus} = \text{Actual Price} - \text{Minimum Acceptable Price}$

Competitive Equilibrium in the Long Run

In the long run, firms enter or exit the market based on profitability, leading to zero economic profit in perfect competition.

• Entry: Profitable markets attract new firms.

• Exit: Unprofitable markets lose firms.

Chapter 7: Perfect Competition and the Invisible Hand

Allocation of Scarce Resources

Markets allocate scarce resources efficiently through price signals, ensuring goods go to those who value them most.

• Example: Tickets for a concert are allocated to those willing to pay the most.

Price Controls

Price controls are government-imposed limits on prices, leading to market distortions.

• Price Ceiling: Maximum legal price; can cause shortages.

• Price Floor: Minimum legal price; can cause surpluses.

Social Surplus and Deadweight Loss

Social surplus is the sum of consumer and producer surplus. Deadweight loss is the reduction in total surplus due to inefficiency.

• Formula: $\text{Social Surplus} = \text{Consumer Surplus} + \text{Producer Surplus}$

• Deadweight Loss: Occurs when market is not at equilibrium, often due to price controls or monopoly.

Chapter 12: Monopoly

Key Characteristics of Monopoly

A monopoly is a market with a single seller, unique product, and significant barriers to entry.

• Single Seller: Only one firm supplies the product.

• Unique Product: No close substitutes.

• Price Maker: The firm sets the price.

Barriers to Entry

Barriers prevent new firms from entering the market, sustaining monopoly power.

• Legal Barriers: Patents, licenses.

• Resource Control: Ownership of key resources.

• Economies of Scale: Large firms have cost advantages.

Profit Maximization in Monopoly

A monopoly maximizes profit where marginal revenue equals marginal cost, but price is set above marginal cost.

• Formula: $MR = MC$

• Price: Determined from the demand curve at the profit-maximizing quantity.

Inefficiencies in Monopoly

Monopolies produce less and charge higher prices than competitive markets, leading to deadweight loss.

• Deadweight Loss: Lost social surplus due to monopoly pricing.

• Example: Pharmaceutical companies with patent-protected drugs.