Question 90

If the radius of a circle is increased by 21%, then its area will increase by what percent?

Solution

Let radius = 10 cm

=> Area of circle = $$\pi (10)^2 = 100 \pi$$ sq. cm

If radius is increased by 21%, => New radius = 12.1 cm

New area = $$\pi (12.1)^2 = 146.41 \pi$$ sq. cm

=> % increase in area = $$\frac{146.41 - 100}{100} \times 100$$

= 46.41%

=> Ans - (D)

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