Ans: D
Consider the range, we have
Consider the range, we have
$\begin{array}{rcl}
61 – (10+a) & = & 42 \\
a & = & 9
\end{array}$
Note that the lower and the upper quartiles are $\dfrac{28+28}{2}=28$ and $\dfrac{40+b+46}{2}= \dfrac{86+b}{2}$ respectively.
Consider the inter-quartile range, we have
$\begin{array}{rcl}
\dfrac{86+b}{2} – 28 & = & 18 \\
b & = & 6
\end{array}$
