Microeconomics: week 8 Perfect Competition, Firm Behavior, and Market Equilibrium Study Guide

Perfect Competition and Market Types

Characteristics of Market Structures

Understanding different market structures is fundamental in microeconomics. The ability of a firm to influence market prices determines the type of market it operates in.

• Perfectly Competitive Market: Many firms, identical products, no single firm can influence the price.

• Monopoly: One firm dominates, can set prices.

• Oligopoly: Few firms, some price-setting power.

• Monopolistic Competition: Many firms, differentiated products.

Example: Agricultural markets (e.g., wheat) are often cited as examples of perfect competition.

Firm Behavior in Perfect Competition

Price Taking and Market Equilibrium

In a perfectly competitive market, firms are price takers. The market sets the price, and individual firms must accept it.

• Market Entrants: Firms that enter the market freely.

• Free Riders: Agents who benefit from resources without paying for them.

• Price Takers: Firms that accept the market price as given.

Example: Wheat farmers in Saskatchewan are price takers.

Revenue and Cost Relationships

Key equations help analyze firm performance in competitive markets.

• Total Revenue (TR): $TR = P \times Q$

• Average Revenue (AR): $AR = \frac{TR}{Q}$

• Marginal Revenue (MR): $MR = \frac{\Delta TR}{\Delta Q}$

• In perfect competition: $AR = MR = P$

Example: If a firm sells 100 units at $5 each,$TR = 5 \times 100 = 500$.

Profit Maximization

Firms maximize profit by producing the quantity where marginal cost equals marginal revenue.

• Profit Maximization Rule: $MR = MC$

• Average Revenue: Total revenue divided by quantity sold.

• Marginal Revenue: Change in total revenue from selling one more unit.

Example: If $MR = 10$ and $MC = 10$, the firm is maximizing profit.

Cost Concepts and Shutdown Decisions

Types of Costs

Understanding cost structures is essential for firm decision-making.

• Fixed Costs (FC): Costs that do not vary with output.

• Variable Costs (VC): Costs that change with output.

• Total Cost (TC): $TC = FC + VC$

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

• Average Variable Cost (AVC): $AVC = \frac{VC}{Q}$

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

Example: If $TC = 100$ and $Q = 10$, $ATC = 10$.

Shutdown Point

A firm should shut down in the short run if the market price falls below average variable cost.

• Shutdown Rule: If $P < AVC$, shut down temporarily.

• Continue Operating: If $P \geq AVC$, continue producing in the short run.

Example: If $AVC = 8$ and $P = 7$, the firm should shut down.

Market Equilibrium and Firm Profit

Market Demand and Supply

Market equilibrium is found where quantity demanded equals quantity supplied.

• Market Demand Equation: $Q^D = a - bP$

• Market Supply Equation: $Q^S = c + dP$

• Equilibrium: Set $Q^D = Q^S$ and solve for $P$.

Example: If $Q^D = 220 - 4P$ and $Q^S = 2P + 40$, set $220 - 4P = 2P + 40$ to solve for $P$.

Firm Profit Calculation

Profit is the difference between total revenue and total cost.

• Profit Formula: $\text{Profit} = TR - TC$

• Economic Profit: Includes opportunity costs.

• Accounting Profit: Excludes opportunity costs.

Example: If $TR = 500$ and $TC = 400$, profit is $100$.

Table: Pat's Pizza Kitchen Cost Structure

The following table shows Pat's Pizza Kitchen's output and total cost, useful for calculating profit-maximizing output and shutdown point.

Output (pizzas per hour)	Total Cost (dollars per hour)
0	10
1	21
2	34
3	41
4	54
5	69

Application: Use the table to calculate average cost, marginal cost, and determine the profit-maximizing output for different market prices.

Summary Table: Key Equations and Rules

Concept	Equation	Rule/Application
Total Revenue (TR)	$TR = P \times Q$	Revenue from sales
Average Revenue (AR)	$AR = \frac{TR}{Q}$	Revenue per unit
Marginal Revenue (MR)	$MR = \frac{\Delta TR}{\Delta Q}$	Change in revenue from one more unit
Average Total Cost (ATC)	$ATC = \frac{TC}{Q}$	Cost per unit
Marginal Cost (MC)	$MC = \frac{\Delta TC}{\Delta Q}$	Change in cost from one more unit
Profit	$\text{Profit} = TR - TC$	Difference between revenue and cost
Shutdown Rule	If $P < AVC$, shut down	Short-run decision
Profit Maximization	$MR = MC$	Optimal output

Additional info:

• Some questions reference the "Wheeler Wheat Farm" as an example of a competitive firm, illustrating the application of cost curves and profit maximization in agriculture.

• Short questions require calculation of profit, economic profit, and shutdown point using provided cost tables and market prices.

• Market demand and supply equations are used to find equilibrium price and quantity, then calculate firm profit and average total cost.