If the sides of a square be double find the increase of percentage in area :

Answer: Option C

\begin{aligned} & {A_1} = {x^2}{\text{ and }}{A_2} = {\left( {2x} \right)^2} = 4{x^2} \\ & {\text{Increase in area}} = \left( {4{x^2} - {x^2}} \right) \\ & \,\,\,\,\,\,\,\,\,\,\,\,\,\,\,\,\,\,\,\,\,\,\,\,\,\,\,\,\,\,\,\,\,\,\,\,\, = 3{x^2} \\ & {\text{Increase % }} = \left( {\frac{{3{x^2}}}{{{x^2}}} \times 100} \right)\% \\ & \,\,\,\,\,\,\,\,\,\,\,\,\,\,\,\,\,\,\,\,\,\,\,\,\,\,\, = 300\% \\\end{aligned}