Question

The length of a rectangular field is increased by 20% and breadth is decreased by 20% . What is the % increase or decrease in its area.

Answer 1

Answer:

Let the length and breadth of the rectangle be l and b respectively.

Now according to the question

If is length is increased by 20%

That means, l * 20/100 = 0.2l => l + 0.2l = 1.2l

Also, b * 20/100 = 0.2b => b - 0.2b = 0.8b

Area of original rectangle will be A = l * b = lb

Area of new rectangle A’ = 1.2l * 0.8b = 0.96 lb

This implies A’ = 0.9 A, where A’ = 192

Therefore 0.96 A = 192

A = 192/0.96 = 200

Area of original rectangle will be 200 sq. units.