The length of a rectangle is increased by 25%, what percentage should the width be decreased so that the areas of the rectangle remains unchanged ?

The length of a rectangle is increased by 25%, what percentage should the width be decreased so that the areas of the rectangle remains unchanged ?

A 20%

B 30%

C 40%

D 25%

Solution

Correct Answer: Option A

Let length = 100x & width =100y

So, area = 100x * 100y

Let p% was decreased

so,

10000xy = (100+25)x*(100y-z)

125xz = 2500xy

=> z = 20y

So % decrease = 20y/100y * 100% = 20%