If the length of a rectangle is increased by 10% and its breadth is decreased by 10%, the change in its area will be-

Let length and breadth be a and b respectively
⇒ The area before change = ab
The length after change = a + 10% of a
= (a + 10a/100)
= (10a + a)/10
= 11a/10
The breadth after change = b - 10% of b
= (b - 10b/100)
= b - b/10
= (10b - b)/10
=9b/10
⇒ The area after change = (11a/10)(9b/10)
⇒ The area after change = 99ab/100

⇒ Percentage change = [{ab - (99ab/100) }/ab] × 100%
= (1/100) × 100%
= 1%
∴ The area of the new rectangle is decreased by 1%.