\(x \propto \sqrt{y}\) i.e., \(x = k\sqrt{y}\) Now, \(2a = k\sqrt{a^2}\) ⇒ \(2a = ka\) ⇒ \(k = 2\) \(\therefore x = 2\sqrt{y}\) [substituting the value of \(k\)] ⇒ \(x^2 = 4y\) [squaring both sides] ⇒ \(\cfrac{x^2}{y} = \cfrac{4}{1}\) ⇒ \(x^2 : y = 4 : 1\) [Answer]