Question 83

If the radius of a circle is increased by 25%, its area increases by:

Solution

Let radius = 10 cm

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

If radius is increased by 25%, => New radius = $$10 + \frac{25}{100} \times 10 = 12.5$$ cm

New area = $$\pi (12.5)^2 = 156.25 \pi$$ sq. cm

=> % increase in area = $$\frac{156.25 - 100}{100} \times 100$$

= 56.25%

=> Ans - (D)

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