The class mark of the class $90-120$ is:

Find the median of the observation: $62, 67, 82, 71, 75, 77, 63, 91$.

The observations $56, 58, 63, x-5, x+1, 75, 81, 85$ have been arranged in ascending order. If the median of the data is $67$,find the value of $x$.

Find the mean of the observations $15, 22, 18, 27, 31, 21, 14, 36, 25$ and $34$.

$A$ grouped frequency distribution table with classes of equal sizes using $63-72$ ($72$ included) as one of the class is constructed for the following data:
$30, 32, 45, 54, 74, 78, 108, 112, 66, 76, 88$
$40, 14, 20, 15, 35, 44, 66, 75, 84, 95, 96$
$102, 110, 88, 74, 112, 14, 34, 44$
The number of classes in the distribution will be:

If the mean of the following data is $20.2,$ find the value of $p:$
$\begin{array}{|c|c|c|c|c|c|} \hline x & 10 & 15 & 20 & 25 & 30 \\ \hline f & 6 & 8 & p & 10 & 6 \\ \hline \end{array}$