According to de-Broglie's equation.
$\lambda=\frac{h}{m v} $
$\Rightarrow \lambda^{2}=\frac{h^{2}}{m^{2} v^{2}}$
or $m v^{2}=\frac{h^{2}}{m \lambda^{2}}$
$\because K E(K)=\frac{1}{2} m v^{2}$
$\therefore K E(K)=\frac{1}{2} \frac{h^{2}}{m \lambda^{2}}$
$\Rightarrow \frac{K_{1}}{K_{2}}=\left(\frac{\lambda_{2}}{\lambda_{2}}\right)^{2}=\left(\frac{5}{3}\right)^{2}$
$\therefore K_{1}: K_{2}=25: 9$