In the class intervals $10-20$ and $20-30$,the number $20$ is included in:

The lengths of $62$ leaves of a plant are measured in millimetres and the data is represented in the following table:

Length (in mm)	Number of leaves
$118-126$	$8$
$127-135$	$10$
$136-144$	$12$
$145-153$	$17$
$154-162$	$7$
$163-171$	$5$
$172-180$	$3$

Draw a histogram to represent the data above.

When the investigator has personally obtained the information for a particular purpose,this data is called ........ data.

The class marks of a continuous distribution are: $1.04, 1.14, 1.24, 1.34, 1.44, 1.54$ and $1.64$. Is it correct to say that the last interval will be $1.55-1.73$? Justify your answer.

The observations $7, 15, x-1, x+1, 24, 28$ have been arranged in ascending order. If the median of the data is $21$,find the value of $x$.

Two sections of Class $IX$ having $30$ students each appeared for a mathematics olympiad. The marks obtained by them are shown below:
$\begin{array}{lllllllllllllll}46 & 31 & 74 & 68 & 42 & 54 & 14 & 61 & 83 & 48 & 37 & 26 & 8 & 64 & 57 \\ 93 & 72 & 53 & 59 & 38 & 16 & 88 & 75 & 56 & 46 & 66 & 45 & 61 & 54 & 27 \\ 27 & 44 & 63 & 58 & 43 & 81 & 64 & 67 & 36 & 49 & 50 & 76 & 38 & 47 & 55 \\ 77 & 62 & 53 & 40 & 71 & 60 & 58 & 45 & 42 & 34 & 46 & 40 & 59 & 42 & 29\end{array}$
Construct a grouped frequency distribution table for the data above using the classes $0-9, 10-19$,etc.,and hence find the number of students who secured more than $49$ marks.