Reading Equilibrium from a Demand-And-Supply Schedule — Market Equilibrium & Price Mechanism | IGCSE Economics

Exam Frequency Analysis

Past paper frequency (2018 to 2024)

This topic accounts for approximately 16% of your exam marks.

stable

Very High

Stable16%

Equilibrium price, surplus/shortage, and price mechanism analysis are core Section B content; tested in most Paper 2 sittings.

A demand-and-supply schedule is a table that lists, for each price, the quantity demanded and the quantity supplied. The equilibrium price is the row where the two columns are equal.

Example — the weekly market for branded headphones at five different prices.

Price (£)	Quantity demanded (units)	Quantity supplied (units)	Difference
40	1,300	400	Shortage = 900
50	1,100	700	Shortage = 400
60	900	900	Equilibrium
70	700	1,100	Surplus = 400
80	500	1,300	Surplus = 800

Reading the table:

The equilibrium price is £60, where Qd = Qs = 900 units.
At £40 and £50 (below the equilibrium), the market is in shortage. At £40 the shortage is 1,300 − 400 = 900 units.
At £70 and £80 (above the equilibrium), the market is in surplus. At £80 the surplus is 1,300 − 500 = 800 units.

Two formulas for numerical questions:

Surplus (above equilibrium) = Qs − Qd.
Shortage (below equilibrium) = Qd − Qs.

Always quote the result with units (e.g. "900 units") and state explicitly whether it is a surplus or a shortage. A bare number with no label scores zero.