Ans: A
Note that the upper-quartile and the lower-quartile are $70$ and $40$ respectively. Hence, the inter-quartile range of the numbers of books read
Note that the upper-quartile and the lower-quartile are $70$ and $40$ respectively. Hence, the inter-quartile range of the numbers of books read
$\begin{array}{cl}
= & 70 – 40 \\
= & 30
\end{array}$
