The radius of a circle is so increased that its circumference

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The radius of a circle is so increased that its circumference increased by 5%. The area of the circle, then increases by

1. 12.5%
2. 10.25%
3. 10.5 %
4. 11.25%
5. None of the above

Correct Option: B

Increase in circumference of circle = 5%
∴ Increase in radius is also 5%.
Now, increase in area of circle = 2a + (a²/100) %
Where, a = increase in radius= 2 x 5 + (5 x 5)/100 % = 10.25%