Question

Find mean:

The marks obtained by 200 students are given below :

Marks	No of students
0-10	5
10-20	10
20-30	11
30-40	20
40-50	27
50-60	38
60-70	40
70-80	09
80-90	14
90-100	6

Answer 1

Mean = $\frac{\sum fixi}{\sum fi}$

Hence, fi = No. of students

xi = class mark

$=\sum fixi=9490$

$=\sum fi=180$

Mean = $\frac{9490}{180}=52.72$