If x = 63% of y, then y2 is approximately what percent of x2 ?

Answer: Option C

x = 63% of y
⇒ x = $$\frac{63y}{100}$$
⇒ y = $$\frac{100x}{63}$$
∴ Required percentage :
$$\begin{array}{rl}& =\left(\frac{y^2}{x^2}\times 100\right)\%\\ & =\left[{\left(\frac{100x}{63}\right)}^2\times \frac{1}{x^2}\times 100\right]\%\\ & =\left(\frac{10000}{3969}\times 100\right)\%\\ & =251.96\%\approx 250\%\end{array}$$