Sep 14, 2016

The original solution has been diluted by a factor of $2 \times {10}^{3}$.
$\text{Final concentration}$
$=$ $\text{Original concentration } \times {10}^{-} 2 \times 2 \times {10}^{-} 1$ $=$
$\frac{1}{2000} \times \text{Original concentration}$.