Question

Define equilibrium price, demand schedule, and supply schedule. Then, briefly explain how demand and supply schedules are used to find the equilibrium price. (4 points)

Answer 1

The equilibrium price is the only price where the desires of consumers and the desires of producers agree—that is, where the amount of the product that consumers want to buy (quantity demanded) is equal to the amount producers want to sell (quantity supplied).

When two lines on a diagram cross, this intersection usually means something. On a graph, the point where the supply curve (S) and the demand curve (D) intersect is the equilibrium.

What Is a Demand Schedule?
In economics, a demand schedule is a table that shows the quantity demanded of a good or service at different price levels. A demand schedule can be graphed as a continuous demand curve on a chart where the Y-axis represents price and the X-axis represents quantity.

An example from the market for gasoline can be shown in the form of a table or a graph. A table that shows the quantity demanded at each price, such as Table 1, is called a demand schedule.

Price (per gallon) Quantity Demanded (millions of gallons)
$1.00 800
$1.20 700
$1.40 600
$1.60 550
$1.80 500
$2.00 460
$2.20 420
Table 1. Price and Quantity Demanded of Gasoline


Supply schedule

again using the market for gasoline as an example. Like demand, supply can be illustrated using a table or a graph. A supply schedule is a table, like Table 2, that shows the quantity supplied at a range of different prices. Again, price is measured in dollars per gallon of gasoline and quantity supplied is measured in millions of gallons.

Price (per gallon) Quantity Supplied (millions of gallons)
$1.00 500
$1.20 550
$1.40 600
$1.60 640
$1.80 680
$2.00 700
$2.20 720
Table 2. Price and Supply of Gasoline

Equilibrium price

gallon) Quantity demanded (millions of gallons) Quantity supplied (millions of gallons)
$1.00 800 500
$1.20 700 550
$1.40 600 600
$1.60 550 640
$1.80 500 680
$2.00 460 700
$2.20 420 720
Table 3. Price, Quantity Demanded, and Quantity Supplied

Because the graphs for demand and supply curves both have price on the vertical axis and quantity on the horizontal axis, the demand curve and supply curve for a particular good or service can appear on the same graph. Together, demand and supply determine the price and the quantity that will be bought and sold in a market.

The equilibrium price is the only price where the plans of consumers and the plans of producers agree—that is, where the amount of the product consumers want to buy (quantity demanded) is equal to the amount producers want to sell (quantity supplied). This common quantity is called the equilibrium quantity. At any other price, the quantity demanded does not equal the quantity supplied, so the market is not in equilibrium at that price.
In Figure 3, the equilibrium price is $1.40 per gallon of gasoline and the equilibrium quantity is 600 million gallons. If you had only the demand and supply schedules, and not the graph, you could find the equilibrium by looking for the price level on the tables where the quantity demanded and the quantity supplied are equal.
The word “equilibrium” means “balance.” If a market is at its equilibrium price and quantity, then it has no reason to move away from that point. However, if a market is not at equilibrium, then economic pressures arise to move the market toward the equilibrium price and the equilibrium quantity.
Imagine, for example, that the price of a gallon of gasoline was above the equilibrium price—that is, instead of $1.40 per gallon, the price is $1.80 per gallon. This above-equilibrium price is illustrated by the dashed horizontal line at the price of $1.80 in Figure 3. At this higher price, the quantity demanded drops from 600 to 500. This decline in quantity reflects how consumers react to the higher price by finding ways to use less gasoline.
Moreover, at this higher price of $1.80, the quantity of gasoline supplied rises from the 600 to 680, as the higher price makes it more profitable for gasoline producers to expand their output. Now, consider how quantity demanded and quantity supplied are related at this above-equilibrium price. Quantity demanded has fallen to 500 gallons, while quantity supplied has risen to 680 gallons. In fact, at any above-equilibrium price, the quantity supplied exceeds the quantity demanded.