Question

Find the mean of the following frequency distribution by step-deviation method :
Class
40-50
50-60
60-70
70-80
80-90
90-100

Frequency
5
10
20
9
6
2

Answer 1

Mean = 70.5 + ( 7/52 ) × 10

= 70.5 + 1.35

= 71.85

Therefore ,

Mean = 71.85

( By Step deviation method )

I hope this helps you.

: )