Momentum is conserved in both $x$ and $y$ directions separately
$$
\begin{array}{ll}
\Rightarrow & m_1 u=m_2 v_2 \cos 30^{\circ} \\
\text { and } & m_1 v_1=m_2 v_2 \sin 30^{\circ}
\end{array}
$$

Also, loss of K E $=50 \%$
$$
\Rightarrow \quad 50=\frac{\frac{1}{2} m_1 u^2-\frac{1}{2} m_1 v_1^2-\frac{1}{2} m_2 v_2^2}{\frac{1}{2} m_1 u^2}
$$

Solving Eqs. (i), (ii) and (iii), we get
$$
\frac{m_2}{m_1}=8
$$