Find the mean of the following data using assume mean method :

Class 0-10 ; F 8

Class 10-20 ; F 12

Class 20-30 ; F 10

Class 30-40 ; F 6

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Solution

Class Frequency(fi) Midpoint of interval(xi) di=xi-a di×fi

0-10 8 5 -10 -80

10-20 12 15 0 0

20-30 10 25 10 100

30-40 6 35 20 120

We have to take the assumed mean from the values in the middle part of xi

We take Assumed mean = 15

Assumed mean, a = 15

So mean = a + (∑di× fi/∑fi)

∑di× fi = -80 + 0 + 100 + 120 = 140

∑fi = 8 + 12 + 10 + 6 = 36

Therefore, Mean = a + (∑di× fi/∑fi)
=15 + (140/36)
= 15 + 3.88
= 18.88

Hence mean by assumed mean method is 18.88

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Q. Find the mean of the following data, by using the assumed mean method.

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= 25

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215

then find

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Find the mean of the following data using Assumed mean method.

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Class	Frequency(fi)	Midpoint of interval(xi)	di=xi-a	di×fi
0-10	8	5	-10	-80
10-20	12	15	0	0
20-30	10	25	10	100
30-40	6	35	20	120

Find the mean of the following data using assume mean method : Class 0-10 ; F 8 Class 10-20 ; F 12 Class 20-30 ; F 10 Class 30-40 ; F 6

Find the mean of the following data using assume mean method :

Class 0-10 ; F 8

Class 10-20 ; F 12

Class 20-30 ; F 10

Class 30-40 ; F 6