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M03.L05 — Cost Curves in Practice: Australian Firm Examples

Module: Module 03 — Production and Costs
Lesson: L05 of 05
Duration: ~30 minutes
Level: Introductory
Provenance: Principles of Microeconomics (Curtis and Irvine) | Khan Academy Microeconomics

Learning Objective

Apply cost curve analysis to real Australian businesses.

Australian Industry Applications

Mining (BHP): - High fixed costs (equipment) - Low marginal costs once producing - Economies of scale in rail/port infrastructure

Retail (Coles): - U-shaped ATC from high initial inventory costs - MC low for additional units sold - Diseconomies in over-expanded stores

Agriculture (GrainCorp): - Seasonal fixed costs (silos) - MP determines optimal harvest labour - Transport costs affect MC curves

Worked Example

Allocative Efficiency: Electricity Market

When wholesale price = \(80/MWh: 1. Snowy Hydro runs hydro plants (MC=\)20) 2. Gas plants run (MC=\(60) 3. Coal plants idle (MC=\)90)

Efficient allocation occurs when P=MC for last unit supplied.

Common Misconception

"Firms always produce at minimum ATC."

Actually, competitive pressures (like Australian supermarkets) may force production where P=MC, which could be above min ATC.

Key Takeaways

  • MC=PL/MPL guides hiring decisions
  • P=MC ensures allocative efficiency
  • P=min ATC is productive efficiency
  • Industry structures shape cost curves

Practice

  1. Why might a mine have high fixed but low marginal costs?
  2. How does Coles' ATC curve differ from BHP's?
  3. When does P=MC benefit society?

Further Resources

Provenance: Principles of Microeconomics (Curtis and Irvine) | Khan Academy Microeconomics