(Q1). The marks obtained in mathematics by 30 students of Class X of a certain school are given in table the below. Find the mean of the marks obtained by the students.

Marks obtained(xi)	10	20	36	40	50	56	60	70	72	80	88	92	95
Number of students(fi)	1	1	3	4	3	2	4	4	1	1	2	3	1

Solution : Let us re-organize this data and find the sum of all observations.

Marks Obtained(xi)	Number of Students(fi)	fixi
10	1	10
20	1	20
36	3
40	4
50	3
56	2
60	4
70	4
72	1
80	1
88	2
92	3
95	1
Total	∑fi =	∑fixi =

So,   x̄ =

∑f_ix_i

∑f_i

=

= .3

Therefore, the mean marks are