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

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?

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?

The points scored by a Kabaddi team in a series of matches are as follows:
$17, 2, 7, 27, 15, 5, 14, 8, 10, 24, 48, 10, 8, 7, 18, 28$
Find the median of the points scored by the team.

Classify the data you can collect from your day-to-day life as primary or secondary data.
In our day-to-day life,we can collect the following data:
$1.$ Number of females per $1000$ males in various states of our country.
$2.$ Weights of students of our class.
$3.$ Production of wheat in the last $10$ years in our country.
$4.$ Number of plants in our locality.
$5.$ Rainfall in our city in the last $10$ years.