Question 52

If the radius of a circle is increased by 15% its area increases by .

Solution

Let radius = 10 cm

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

If radius is increased by 15%, => New radius = $$10 + \frac{15}{100} \times 10 = 11.5$$ cm

New area = $$\pi (11.5)^2 = 132.25 \pi$$ sq. cm

=> % increase in area = $$\frac{132.25 - 100}{100} \times 100$$

= 32.25%

=> Ans - (B)

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