A small town is served by many competing supermarkets, which all have the same constant marginal cost.

Use the black point (plus symbol) to show the competitive price and quantity in this market. Then use the green area (triangle symbol) to shade the area representing consumer surplus in the market for groceries, and use the purple area (diamond symbol) to shade the area representing producer surplus.

Monopoly Demand + Monopoly Outcome A Consumer Surplus Marginal Cost Price, Cost, Revenue Producer Surplus Deadweight Loss Marginal Revenue Quantity of GroceriesCompetitive Market Demand Competitive Outcome A Consumer Surplus Marginal Cost Price, Cost, Revenue Producer Surplus Quantity of Groceries