Think of the market as a busy street market. The price is like a traffic light that tells sellers how much to produce and buyers how much to buy.
Mathematically we write the demand and supply functions as:
\$D(p) = 100 - 2p\$ and \$S(p) = 2p\$
Here \$p\$ is the price, \$D(p)\$ is the quantity demanded and \$S(p)\$ is the quantity supplied.
When the price is low, many buyers want the good (high demand) but few sellers are willing to produce it (low supply). As the price rises, sellers are encouraged to produce more and buyers are discouraged from buying too much.
📈 Equilibrium occurs where demand equals supply: \$D(p^*) = S(p^*)\$. Solve the equations to find the equilibrium price \$p^*\$ and quantity \$Q^*\$.
| Price ($) | Quantity Demanded (Qd) | Quantity Supplied (Qs) |
|---|---|---|
| 0 | 100 | 0 |
| 10 | 80 | 20 |
| 20 | 60 | 40 |
| 30 | 40 | 60 |
| 40 | 20 | 80 |
| 50 | 0 | 100 |
When solving for equilibrium, set the demand and supply equations equal: \$100 - 2p = 2p\$. Then isolate \$p\$ and substitute back to find \$Q\$. Show all steps clearly.
When the market price is too high, excess supply means some goods are left unsold. Sellers may ration by limiting the quantity each buyer can purchase.
Example: A school sells lunch tickets at $5 each. If only 50 tickets are sold but 100 are available, the school might limit each student to 1 ticket to ensure everyone gets a meal.
⚖️ Rationing is a way to use price signals to manage scarcity without changing the price itself.
Identify situations where the price is above or below equilibrium. Explain how rationing would occur and what impact it has on consumer surplus.
Prices act as signals that show how much people value a good. If a good becomes very expensive, it signals that many people want it.
These signals help producers decide how much to produce and consumers decide whether to buy.
When asked about signalling, describe how a price change reflects changes in preferences and how this influences future supply and demand.
Prices can incentivise behaviour. Higher prices can discourage consumption, while lower prices can encourage it.
In economics, we call this the price mechanism – it steers resources to where they are most valued.
Use the concept of the price mechanism to explain how changes in price can lead to changes in quantity demanded or supplied. Include the idea of consumer and producer surplus where relevant.