Ans: B
Let $\sigma$ marks be the standard deviation of the scores of the Mathematics examination.
Let $\sigma$ marks be the standard deviation of the scores of the Mathematics examination.
$\begin{array}{rcl}
\dfrac{33 – 45}{\sigma} & = & -2 \\
-12 & = & -2 \sigma \\
\sigma & = & 6
\end{array}$
Therefore, the standard deviation of the scores of the Mathematics examination is $6$ marks.
