Compute the typical de-Broglie wave length of an electron in a metal at $27^{\circ}$ C and compare it with the mean separation between two electron in a metal which given to be about $2 \times 10^{-10}\;m$

Question

$\begin{array}{1 1} \frac{\lambda}{r} =313 \\ \frac{\lambda}{r} =31.3 \\ \frac{\lambda}{r} =3.13 \\ \frac{\lambda}{r} =0.313 \end{array} $