Question

Calculate arithmetic mean by step deviation method. 5 marks Need not show entire calculations , just write the final answer but with steps written in words with which you arrived at the final answer.​

Answer 1

Answer:

Mid point (X) Frequency (F) i=class interval width A=50 Assumed Means d'=

i

x−A

fd'

20-40 30 4 20 50 -1 -4

40-60 50=A 8 20 50 0 0

60-80 70 12 20 50 1 12

80-100 90 16 20 50 2 32

Σf=40 Σfd

′

=40

The formula used for arithmetic mean of grouped data by step deviation method is,

X

=A+

∑f

∑fd

′

×i

A= Assumed mean of the given data

∑ = Summation of the frequencies given in the grouped data

∑fd

′

= Summation of the frequencies and deviation of a given mean data

d

′

=

i

(x−A)

i= Class interval width

X

= arithmetic mean

X

=50+

40

40

×20

=50+20

=70