Answer
Please see the work below.
Work Step by Step
We know that
$KE=(\frac{1}{2})mv^2$
This simplifies to
$v=\sqrt{\frac{2KE}{m}}$
Hence the required ratio is
$\frac{v_1}{v_2}=(\sqrt{\frac{KE_1}{KE_2}})(\sqrt{\frac{m_2}{m_1}})=(\sqrt{1}{1})(\sqrt{\frac{1}{4}})=0.5$
