Due to 10% fall in price of X, its demand rises from 100 units to 120 units. How much prercent will its demand fall due to 10% in its price ?

Explanation

we need to first find `% DeltaQ`
`DeltaQ= Q_(1)-Q`
120-100=20 units
`% DeltaQ= (deltaQ)Qxx100=20/100xx100=20%`
`P.e_(D) = (%DeltaQ)/(%DeltaP) = (+20%)/((-)10%)= (-)2`
`P.e_(D)=-2or |p.e_(D)|=2`
Now when price rises by 10%:
`P.e_(D)= (%DeltaQ)/(%DeltaP)`
`-2= (%DeltaQ)/(+10%)= %DeltaQ=-20%`
Quantity demanded of the food falls by 20%.