Question

Use Step-Deviation Method to find mean :Value of x
5
10
15
20
25
30
35
40
45
50

Frequency [f]
20
43
75
67
72
45
39
8
9
6

Answer 1

Step - deviation method :

From the table ,

a = assumed mean = 25

Sum of the frequencies = Sigma fi = 384,

di = xi - a ,

ui = di/h

Sigma ( fiui ) = 213

Now ,

Mean = a + [( sigma fiui )/( sigma fi )]× h

= 25 + ( 213/384 )× 5

= 25 + 1065/384

= 25 + 2.773

= 27.773

Therefore,

Mean = 27.773

••••

Answer 2

Answer:

assumed mean =25

X1= d/5

mean =27.77