Derive the demand curve, classify goods, distinguish shifts from movements, and aggregate market demand.
How changing price alters the optimal choice, tracing out the demand curve.
The demand curve is derived directly from a consumer's optimal choices when facing a budget constraint. By keeping income and preferences constant, we can observe how the optimal consumption bundle changes as the price of a good falls.
Matrix comparing Normal/Inferior and Substitute/Complement goods.
Visual distinction between moving along the curve and shifting it.
A shift occurs when external factors (like income or preferences) change, moving the entire curve.
A movement along the curve occurs strictly when the price of the good itself changes.
MCQ testing the cause of a demand curve shift.
If the price of coffee increases, what happens to the demand curve for tea?
Transitioning from individual to total market demand via horizontal summation.
While an individual demand curve shows what a single consumer wants, an economy relies on the aggregation of all buyers. Market demand is the total quantity of a good that all consumers in the market are willing to buy at a specific price.
Algebraic summation of two piecewise linear demand equations.
Problem. Consider a market with exactly two consumers. Their individual linear demand curves are given by: Consumer 1: Consumer 2: Find the combined market demand function.
Calculating market demand for specific prices using the piecewise logic.
Consider a market where there are two consumers with linear demand curves given by and . We need to calculate the total market demand at three specific price levels: , , and . At , both consumers are willing to buy the good because the price is below their respective maximums. Consumer 1 demands units, and consumer 2 demands units, yielding a total market demand of units. At , consumer 1 demands 0 units because the price is greater than 10, while consumer 2 demands units. Thus, the total market demand at this price is units. Finally, at , the price exceeds the maximum willingness to pay for both consumers. As a result, neither consumer can afford the good, making the market demand exactly units.