2ClassNotes.com - Home
Banner Here

Search

ePapers

Central Board of Secondary Education

All

10

Mathematics

   

Search for

Keyword

Statistics - Assumed Mean Method

This is the formula for calculating mean with assumed mean method

Mathematics [All]

Central Board of Secondary Education [10]

Statistics - Assumed Mean Method [57.21 KB]

1/23/2009Print This PageTell - A - FriendAdd to Wish ListReport Error

Like its, name in this method we assume a number as the mean of the given data. Then we subtract this assumed mean from all class marks. Hence find di.

Let a is our assumed mean and  x1, x2, x3 .......xn are the class marks. Then

d1 = x1 - a

d2 = x2 - a

d3 = x3 - a

-------------

-------------

dn = xn - a

Collectively we can write

di = xi - a

After that we calculate

fi di = f1 d1 + f2 d2 + f3 d3 + ------- + fn dn

Now



Since di = xi - a

Therefore


This is the formula for calculating mean with assumed mean method. The method will be more clear with following example

Note :  You can assume any number as assumed mean (a) but the general choice is any xi which lies in the middle of range of xi.

Example: Calculate the mean of following data with the help of assumed mean method.
 

C. I

10 - 20

20 - 30

30 - 40

40 - 50

50 - 60

60 - 70

70 - 80

80 - 90

90 - 100

100 - 110

fi

4

5

4

4

3

4

16

13

11

16


Solution:

C . I .

xi

fi

d = xi - a

fid

10 20

15

4

-40

-160

20 -30

25

5

-30

-150

30 - 40

35

4

-20

-80

40 - 50

45

4

-10

-40

50 - 60

55 a

3

0

0

60 -70

65

4

10

40

70 -80

75

16

20

320

80 -90

85

13

30

390

90 - 100

95

11

40

440

100 - 110

105

16

50

800

   

fi = 80

 

fi di = 1560

Let a = 55

Now


= 55 + (1560 / 80)

= 55 + 19.5

= 74.5

1/23/2009Print This PageTell - A - FriendAdd to Wish ListReport Error

Related Words:

Mean Method, Median Method, Mode Method, Statistics, Class 10 Statistics

LOGIN

Username

Password

New UserForgot Password