$\Delta x.\,\Delta v = \frac{h}{{4\pi m}}$

                   [Heisenberg' uncertainty principle]

or $\Delta x = \frac{h}{{4\pi m.\Delta v}}$

Thus, $\Delta {x_A} = \frac{h}{{4\pi  \times 0.05 \times m}}....(i)$

          $\Delta {x_B} = \frac{h}{{4\pi  \times 0.02 \times 5m}}....(ii)$

Dividing $(i)$ by $(ii)$, we get 

$\frac{{\Delta {x_A}}}{{\Delta {x_B}}} = \frac{{0.02 \times 5}}{{0.05}} = \frac{{10}}{5}\,or\,2$