Total Surplus

Concepts of demand relate to various buyers' willingness to pay.
Willingness to pay can be arranged from highest to lowest.
The maximum willingness to pay is set at $4,000,000.
The marginal buyer is defined as the purchaser who is willing to pay just enough to enter the market but would leave if the price increased.
Determination of the marginal buyer's willingness to pay helps in understanding market dynamics.

Definition: Consumer surplus is the area below the demand curve and above the market price.
Two types of demand curves:
- Staircase Demand Curve: Consumer surplus is represented by a series of rectangles.
- Smooth Demand Curve: Consumer surplus is represented by a triangular area.
Mathematical representation using geometry is crucial to calculate consumer surplus.

Definition: Producer surplus measures the benefit that producers gain from participating in the market, calculated as:
\text{Producer Surplus} = \text{Price received} - \text{Cost of production}
The supply curve has been reimagined as a cost curve, determining the costs for all suppliers.
The marginal seller is defined as the lowest-priced seller who would stop selling if the price were lower.
To compute total producer surplus:
- For staircase supply, total producer surplus is calculated as a series of rectangles.
- For smooth supply, total producer surplus is computed as a triangular area below the price line and above the supply curve.

Example with Three Buyers (Alison, Bob, Therese): Their willingness to pay decreases with each successive purchase.
- Alison: First orange - $2, second - $1.50, third - $0.75.
- Calculation of change in consumer surplus when price decreases from $1.00 to $0.76:
- Alison's increase:
  - Buys 3 oranges (previously 2) at 30 cents less for each of the first two, gaining an additional 5 cents from the third orange.
  - Total consumer surplus gain: 30 cents + 30 cents + 5 cents = 65 cents.
- Bob’s response:
  - Previously bought 2 oranges, does not alter his buying behavior; gain = 60 cents.
- Therese: Previously bought 0 oranges, now buys 1 orange and gains 5 cents.
- Conclusion: Alison has the largest increase in consumer surplus.

Analyzing how price changes affect producer surplus using a smooth supply curve as an example with chocolate cakes.
At a production level of 15 units, the marginal cost is $30 and if the price is $40, the individual producer surplus = $10 per unit.
To find total producer surplus:
- Total area is a triangle formed below price and above the supply curve, computed as:
  \text{Area} = \frac{1}{2} \times \text{base} \times \text{height} .
- Ensure diminishing dimensions of the triangle are calculated properly, avoiding errors with starting point assumptions.

Efficiency in a market occurs when total surplus (sum of consumer and producer surplus) is maximized.
Total surplus can be visualized as the area between supply and demand curves.
At equilibrium, both consumer and producer surplus need to be analyzed:
- Consumer surplus = area below demand and above price.
- Producer surplus = area below price and above supply.
- Total surplus is maximized at equilibrium:
  \text{Total Surplus} = \text{Consumer Surplus} + \text{Producer Surplus} .
Surplus is maximized when resources are allocated efficiently to those who value them most highly, leading to optimal production by the lowest-cost producers.

Price increase mechanics: Every current seller benefits from a higher price and new sellers enter the market.
Conversely, if the price decreases, producer surplus decreases in two ways:
- Existing sellers earn less per unit.
- Higher-cost sellers exit the market, reducing the number of units available.
Example scenario: $40 to $30 price drop leads to changes in producer surplus calculations.

Comparison of market-driven economies versus centrally planned economies:
- Central planners require comprehensive knowledge of every seller's costs and buyers’ willingness to pay, which is practically impossible.
- Market systems rely on prices to guide resource allocation, making them efficient under normal circumstances.
- Recognition of government intervention in cases of market failures is necessary for future discussions.