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Market Supply and Producer Surplus

Sep 13, 2025

Overview

This lecture explains how individual supply schedules combine to form the market supply curve, introduces the supply curve equation, and defines producer surplus.

From Individual Supply to Market Supply

  • The market supply schedule is found by adding quantities supplied by all firms at each price point.
  • Example: If Antonio, Blanca, and Carmen supply 350, 1000, and 2000 pizzas respectively at $1, the market supply is 3350 at that price.
  • A graph is created with price on the y-axis and quantity on the x-axis to show the market supply curve.

Market Supply Curve and Its Equation

  • The market supply curve can be represented with a linear equation, e.g., Q = 100P.
  • When price (P) is zero, quantity supplied (Q) is zero; as price increases, so does quantity supplied.
  • This straight line shows the positive relationship between price and quantity supplied.

Interpretation of the Market Supply Curve

  • The market supply curve shows the minimum price at which producers are willing to sell each quantity (willingness to sell).
  • Under the assumption that firms are price takers, the supply curve is also the marginal cost curve, showing the lowest price producers accept for each unit.
  • At a given price, the supply curve shows the maximum quantity the market supplies, including both producers willing to sell for less and those just willing at that price.

Producer Surplus

  • Producer surplus is the difference between what a producer is willing to accept and the actual market price.
  • Example: If a producer is willing to sell at $3 but sells at $5, the producer surplus is $2 per unit.
  • Producer surplus is an important concept for market analysis discussed further in later lessons.

Key Terms & Definitions

  • Market Supply — The total quantity offered at each price by all producers in a market.
  • Supply Curve — A graph showing the relationship between price and quantity supplied.
  • Marginal Cost Curve — A curve indicating the minimum price producers accept for each unit; for price takers, this is the supply curve.
  • Producer Surplus — The benefit producers receive when the market price exceeds their minimum acceptable price.

Action Items / Next Steps

  • Review how to construct market supply curves from individual supply schedules.
  • Understand and practice interpreting supply curve equations (e.g., Q = 100P).