Current Electricity

The area of cross-section of a copper wire is $4 \times 10^{-7} \mathrm{~m}^2$ and the electrons per cubic metre in copper is $8 \times 10^{28}$. If the wire carries a current of 6.4 A , then the drift velocity of the electrons ( $\mathrm{in} 10^{-3} \mathrm{~ms}^{-1}$ ) is