Answer
See the detailed answer below.
Work Step by Step
This is a case involving the Heisenberg Uncertainty Principle, which relates the uncertainty in position $\Delta x $ and the uncertainty in momentum $\Delta p_x $ where
$$ \Delta x \cdot \Delta p_x \geq \frac{h}{2}\tag 1 $$
According to the Heisenberg uncertainty principle, Andrea's position uncertainty inside the room could be as large as the room's length.
So,
$$\Delta x=5\;\rm m\tag 2$$
The uncertainty in Andrea's velocity $\Delta v_x $ can be found by
$$ \Delta p_x = m \Delta v_x $$
Plug into (1);
$$m \Delta v_x\geq \frac{h}{2 \Delta x} $$
Hence,
$$ \Delta v_x \geq \frac{h}{2m_e \Delta x} $$
Plug the known;
$$ \Delta v_x \geq \frac{(6.63\times 10^{-34})}{2(50) (5)}=\bf 1.33\times 10^{-36}\;\rm m/s $$
And since her average velocity is zero, her velocity range is then
$$\boxed{-6.6\times 10^{-37}\;{\rm m/s}\leq 6.6\times 10^{-37}\leq \;{\rm m/s}}$$
