If radius of a circle is increased by 5%, then the increase in it's area is :

Answer: Option A

Quicker approach
$$\uparrow$$   in A = a + b + $$\frac{ab}{100}$$
Here a = b = 5%
$$\uparrow$$   in A :
$$\begin{array}{rl}& =\left(5+5+\frac{5\times 5}{100}\right)\%\\ & =10.25\%\end{array}$$