A body is dropped on ground from a height h _ 1 and after hitting...

The given ratio of the velocities is

$\dfrac{{v}_{1}}{{v}_{2}} = 4$

The percentage loss in kinetic energy is

$\dfrac{\dfrac{m{v}^{2}1}{2} - \dfrac{m{v}^{2}2}{2}}{\dfrac{m{v}^{2}1}{2}} \times 100 = \dfrac{x}{4} ⇒ \dfrac{{v}^{2}1 - {v}^{2}2}{{v}^{2}1} = \dfrac{x}{400} ⇒ 1 - \dfrac{{v}^{2}2}{{v}^{2}1} = \dfrac{x}{400} ⇒ 1 - \dfrac{1}{16} = \dfrac{x}{400} ⇒ x = 375$