Consider the marks obtained (out of $100$ marks) by $30$ students of Class $IX$ of a school:
$\begin{array}{*{20}{c}}
{10}&{20}&{36}&{92}&{95}&{40}&{50}&{56}&{60}&{70} \\
{92}&{88}&{80}&{70}&{72}&{70}&{36}&{40}&{36}&{40} \\
{92}&{40}&{50}&{50}&{56}&{60}&{70}&{60}&{60}&{88}
\end{array}$

Van Mahotsava was celebrated in $100$ schools,where $100$ plants were planted in each school. After one month,the number of plants that survived were recorded as follows:
$\begin{array}{llllllllll}95 & 67 & 28 & 32 & 65 & 65 & 69 & 33 & 98 & 96 \\ 76 & 42 & 32 & 38 & 42 & 40 & 40 & 69 & 95 & 92 \\ 75 & 83 & 76 & 83 & 85 & 62 & 37 & 65 & 63 & 42 \\ 89 & 65 & 73 & 81 & 49 & 52 & 64 & 76 & 83 & 92 \\ 93 & 68 & 52 & 79 & 81 & 83 & 59 & 82 & 75 & 82 \\ 86 & 90 & 44 & 62 & 31 & 36 & 38 & 42 & 39 & 83 \\ 87 & 56 & 58 & 23 & 35 & 76 & 83 & 85 & 30 & 68 \\ 69 & 83 & 86 & 43 & 45 & 39 & 83 & 75 & 66 & 83 \\ 92 & 75 & 89 & 66 & 91 & 27 & 88 & 89 & 93 & 42 \\ 53 & 69 & 90 & 55 & 66 & 49 & 52 & 83 & 34 & 36\end{array}$

The following observations have been arranged in ascending order. If the median of the data is $63$,find the value of $x.$
$29, 32, 48, 50, x, x+ 2, 72, 78, 84, 95$

$A$ company manufactures car batteries of a particular type. The lives (in years) of $40$ such batteries were recorded as follows:
$\begin{array}{llllllll}2.6 & 3.0 & 3.7 & 3.2 & 2.2 & 4.1 & 3.5 & 4.5 \\ 3.5 & 2.3 & 3.2 & 3.4 & 3.8 & 3.2 & 4.6 & 3.7 \\ 2.5 & 4.4 & 3.4 & 3.3 & 2.9 & 3.0 & 4.3 & 2.8 \\ 3.5 & 3.2 & 3.9 & 3.2 & 3.2 & 3.1 & 3.7 & 3.4 \\ 4.6 & 3.8 & 3.2 & 2.6 & 3.5 & 4.2 & 2.9 & 3.6\end{array}$
Construct a grouped frequency distribution table for this data,using class intervals of size $0.5$ starting from the interval $2 - 2.5$.

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?

Thirty children were asked about the number of hours they watched $TV$ programmes in the previous week. The results were found as follows:
$\begin{array}{rrrrrrrrrr}1 & 6 & 2 & 3 & 5 & 12 & 5 & 8 & 4 & 8 \\ 10 & 3 & 4 & 12 & 2 & 8 & 15 & 1 & 17 & 6 \\ 3 & 2 & 8 & 5 & 9 & 6 & 8 & 7 & 14 & 12\end{array}$
$(i)$ Make a grouped frequency distribution table for this data,taking class width $5$ and one of the class intervals as $5-10$.
$(ii)$ How many children watched television for $15$ or more hours a week?