Question

Marks of $30$ students in mathematics test are given in the adjacent grouped frequency distribution.

Sl. No	Marks	No of students
$1$	$0-5$	$5$
$2$	$5-10$	$7$
$3$	$10-15$	$10$
$4$	$15-20$	$6$
$5$	$20-25$	$2$

If a student gets $10$ marks, should he be included in $2nd$ or $3rd$ class?

Answer 1

$\Rightarrow$ The first column here represents the marks obtained in class interval form. The lowest number in a class interval is called the lower limit and the highest number is called the upper limit. This example is a case of continuous class intervals as the upper limit of one class is the lower limit of the following class.

$\Rightarrow$ In continuous cases, any observation corresponding to the extreme values of a class is always included in that class where it is the lower limit. For example, if we had a student who has scored $5$ marks in the test, his marks would be included in the class interval $5-10$ and not $0-5.$

$\therefore$ A student gets $10$ marks, should be included in $3^{rd}$ group.