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

• A. 10.25%
• B. 12.5%
• C. 10.5 %
• D. 11.25%

Answer: (A)

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%