When price of a commodity X falls by 10 percent , its demand rises from 150 units to 180 units. Calculate its price elasticity of demand . How much should be the percentage fall in its price so that its demand rises from 150 to 210 units.

Explanation

`E_(P)=(% " change in " Q_(d))/(% " change in P")=((30)/(150)xx100)/(-10)=(-2)`
`-2=((60)/(150)xx100)/(%" change in price")`
`%` change in Price `=(60)/(150)xx100xx(1)/(-2)=-20%`.