A body thrown upwards with some velocity reaches the maximum height of  50m. Another body with double the mass thrown up with double the initial velocity will reach a maximum height of…………

Let ‘u’ be the initial velocity of the body in the first case.
Given the maximum height reached H=50m

$\Rightarrow \frac{u^2}{2g}=\mathrm{50..........}\left(i\right)$

If the initial velocity is doubled then the maximum height reached 

$\begin{array}{l}{H}^1=\frac{(2u{)}^2}{2g}\\ =4\left(\frac{u^2}{2g}\right)\\ =4\left(50\right)\\ =200m\end{array}$