Question

marks 0-10, 10-20, 20-30, 30-40, 50-60, 60-70, 70-80, 80-90, 90-100, Frequency 5, 11, 10, 20, 28, 37, 40, 29, 14, 6 find mean by shortcut method​

Answer 1

Step-by-step explanation:

X Mid Point (X) Frequency (F) i=class interval width A=45 Assumed mean u=

i

x−A

fu

0-10 5 3 10 45 -4 -12

10-20 15 5 10 45 -3 -15

20-30 25 6 10 45 -2 -12

30-40 35 7 10 45 -1 -7

40-50 45=A 8 10 45 0 0

50-60 55 9 10 45 1 9

60-70 65 10 10 45 2 20

70-80 75 12 10 45 3 36

80-90 85 6 10 45 4 24

90-100 95 4 10 45 5 20

Σf=70 Σfu=63

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

X

=A+

∑f

∑fu

×i

A= Assumed mean of the given data

∑ = Summation of the frequencies given in the grouped data

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

u=

i

(x−A)

i= Class interval width

X

= arithmetic mean

X

=45+

70

63

×10

=45+9

=54

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