Question

A class teacher has the following absentee record of $40$ students of a class for the whole term. Find the mean number of days a student was absent.

Number of days:	0-6	6-10	10-14	14-20	20-28	28-38	38-40
Number of students:	$11$	$10$	$7$	$4$	$4$	$3$	$1$

Answer 1

Answer:-

No. of days	No. of student $f_i$	$x_i$	$f_i{x}_i$
0-6	11	3	33
6 - 10	10	8	80
10 - 14	7	12	84
14 - 20	4	17	68
20 - 28	4	24	96
28 - 38	3	33	99
38 - 40	1	39	39
	$\Sigma f_i=40$		$\Sigma f_i{x}_i=499$

The mean number of days a student was absent $=\frac{\Sigma f_i{x}_i}{\Sigma f_i}=\frac{499}{40}=12.475$

Hence, the mean number of days a student was absent is $\mathrm{12.475.}$