If the marks obtained by the $20$ students are $6, 4, 9, 5, 9, 3, 7, 7, 5, 6, 9, 4, 10, 10, 4, 3, 6, 7, 9, 9$,then the mode of this data is .............

The frequency distribution of the marks scored by $35$ students in a $60$ marks test is as below:

Marks scored	No. of students
$0-10$	$2$
$10-20$	$7$
$20-30$	$8$
$30-40$	$7$
$40-50$	$8$
$50-60$	$3$

Represent the data by a histogram.

Find the mean and the median of the observations: $72, 15, 28, 31, 32, 51, 44, 43$ and $62$.

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.

Draw a histogram for the data given below:

Class	$0-6$	$6-12$	$12-18$	$18-24$	$24-30$	$30-36$
Frequency	$7$	$10$	$12$	$15$	$10$	$6$

The marks obtained by $17$ students in a mathematics test (out of $100$) are given below:
$91, 82, 100, 100, 96, 65, 82, 76, 79, 90, 46, 64, 72, 68, 66, 48, 49$
The range of the data is: