$a_{1}=\frac{2 q E}{m}$ and $a_{2}=\frac{q E}{2 m}$

Their final velocities after time $\mathrm{t},$

${\mathrm{v}=0+\mathrm{at}=\mathrm{at}} $

$\mathrm{v}_{1}=\frac{2 \mathrm{q} \mathrm{E}}{\mathrm{m}} \mathrm{t}$ and $\mathrm{v}_{2}=\frac{\mathrm{q} \mathrm{E}}{2 \mathrm{m}} \mathrm{t}$

Ratio of kinetic energy of the two particles

$\frac{\mathrm{K}_{1}}{\mathrm{K}_{2}}=\frac{\frac{1}{2} \mathrm{mv}_{1}^{2}}{\frac{1}{2} 2 \mathrm{mv}_{2}^{2}}=\frac{\mathrm{v}_{1}^{2}}{2 \mathrm{v}_{2}^{2}}=\frac{8}{1}$