$i = neAv _{ d }$

Calculate the value of $n$ as follows.

$n =\frac{ N _{ A }}{ V } \times \frac{ M }{ m _{ W }}$

$=\frac{ N _{ A } \rho}{ m _{ w }}$

$=\frac{6 \times 10^{23} \times 2.7 \times 10^{3}}{27 \times 10^{-3}}$

$=6 \times 10^{28}$

Substitute the values in the above expression.

$i = neAV _{ d }$

$v _{ d }=\frac{ i }{ neA }$

$=\frac{10 \times 10^{19}}{6 \times 10^{28} \times 4 \times 10^{-6} \times 1.6}$

$=2.6 \times 10^{-4} m / s$