Find the median of the observations $18, 8, 12, 3, 20, 4, 10, 5$.

The following table gives the frequencies of most commonly used letters $a, e, i, o, r, t, u$ from a page of a book:

Letters	$a$	$e$	$i$	$o$	$r$	$t$	$u$
Frequency	$75$	$125$	$80$	$70$	$80$	$95$	$75$

Represent the information above by a bar graph.

The median of the data $78, 56, 22, 34, 45, 54, 39, 54, 84$ is

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 $x$.

The following table shows a frequency distribution for the speed of cars passing through a particular spot on a highway:

Class interval $(km/h)$	Frequency
$30-40$	$3$
$40-50$	$6$
$50-60$	$25$
$60-70$	$65$
$70-80$	$50$
$80-90$	$28$
$90-100$	$14$

Draw the frequency polygon representing the above data without drawing the histogram.

The following table gives the distribution of students of sections $A$ and $B$ of a class according to the marks obtained by them.

Marks	Section $A$ Frequency	Section $B$ Frequency
$0-15$	$3$	$3$
$15-30$	$12$	$16$
$30-45$	$28$	$25$
$45-60$	$30$	$27$
$60-75$	$35$	$40$
$75-90$	$13$	$10$

Represent the marks of the students of both the sections on the same graph by two frequency polygons. What do you observe?