Find the mean of the marks obtained by $30$ students of Class $IX$ of a school.
$\begin{array}{llllllllll}10 & 20 & 36 & 92 & 95 & 40 & 50 & 56 & 60 & 70 \\ 92 & 88 & 80 & 70 & 72 & 70 & 36 & 40 & 36 & 40 \\ 92 & 40 & 50 & 50 & 56 & 60 & 70 & 60 & 60 & 88\end{array}$

The blood groups of $30$ students of Class $VIII$ are recorded as follows:
$A, B, O, O, AB, O, A, O, B, A, O, B, A, O, O,$
$A, AB, O, A, A, O, O, AB, B, A, O, B, A, B, O.$
Represent this data in the form of a frequency distribution table. Which is the most common,and which is the rarest,blood group among these students?

Find the mode of the following marks (out of $10$) obtained by $20$ students:
$4, 6, 5, 9, 3, 2, 7, 7, 6, 5, 4, 9, 10, 10, 3, 4, 7, 6, 9, 9$

The heights (in $cm$) of $9$ students of a class are as follows:
$155, 160, 145, 149, 150, 147, 152, 144, 148$
Find the median of this data. (in $\text{ cm}$)

The following table gives the life times of $400$ neon lamps:

The time (in hours)	Number of lamps
$300-400$	$14$
$400-500$	$56$
$500-600$	$60$
$600-700$	$86$
$700-800$	$74$
$800-900$	$62$
$900-1000$	$48$

$(i)$ Represent the given information with the help of a histogram.
$(ii)$ How many lamps have a life time of more than $700$ hours?

In a mathematics test given to $15$ students,the following marks (out of $100$) are recorded:
$41, 39, 48, 52, 46, 62, 54, 40, 96, 52, 98, 40, 42, 52, 60$
Find the mean,median,and mode of this data.