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