The elasticity of demand can be calculated by dividing the percentage change in the quantity demanded of a good or service by the percentage change in price.
The data for point C are: Price=$6, Quantity=8
The data for point D are: Price=$4, Quantity=12
The percent change in the quantity demanded is:
We calculated the ratio instead of the percentage, but it will work fine.
The percent change in price is:
The elasticity of demand is:
Since the absolute value of the elasticity is greater than one, the demand is said to be elastic.