We saw that we can express demand and supply relationships in a table of prices and corresponding quantities demanded and supplied. We can use such tables to find equilibrium quantity and price, or at least approximate them, depending on the available data.

Table A     Table B
 MarketPrice QuantityDemanded QuantitySupplied 0 60 0 5 50 10 10 40 20 15 30 30 20 20 40 25 10 50

 MarketPrice QuantityDemanded QuantitySupplied 0 10 0 1 9 1 2 7 3 3 6 5 4 4 7 5 3 9

In Table A, the row corresponding to a market price of 15 is highlighted. At this price, Quantity Demanded and Quantity Supplied are equal. It is easy to see that the equilibrium price is 15 and the equilibrium quantity is 30.

Equilibrium is not as obvious for the data in Table B. There is no row where Quantity Demanded and Quantity Supplied are equal. We highlight two rows that will help us estimate equilibrium price and quantity. At a price of 3, Quantity Demanded is greater than Quantity Supplied and a price of 4, the reverse is true. From this we can tell that the equilibrium price will be greater than 3 and less than 4, and the equilibrium quantity will be less than 7 but greater than 5. Even though the data in Table B don't give us the exact equilibrium price and quantity, they allow us to estimate that equilibrium price is probably close to 3.5 and equilibrium quantity is probably close to 6.

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