The width of the rectangle was increased by 10% and its length was decreased by 10%.

The width of the rectangle was increased by 10% and its length was decreased by 10%. Did the area of the rectangle change in this case? If it has changed, has it increased or decreased?

Let the sides of the rectangle be a and b, respectively. And its area is s = a ∙ b.

The modified sides of the new rectangle will be (9/10) ∙ a and (11/10) ∙ b.

Find the area of the new rectangle: S = (9/10) ∙ (11/10) ∙ a ∙ b = (99/100) ∙ a ∙ b.

We see that S = (99/100) ∙ s <s.

Answer: The area of the rectangle will change. It will decrease by 1/100 (one hundredth).