In Biology test the
following marks were recorded.
marks

1019

2029

3039

4049

5059

No. of students

2

4

5

6

3

Calculate the mean.
Solution
In this question we are
going to apply the method of assumed mean.
Here you are required to
produce the frequency distribution table.
Let us take 34.5 as our
assumed mean(A). Take away the assumed mean from each class mark.
Class
interval

Class mark
(x)

d=xA

Frequency(f)

fx

fd

1019

14.5

20

2

29

40

2029

24.5

10

4

98

40

3039

34.5

0

5

172.5

0

4049

44.5

10

6

267

60

5059

54.5

20

3

163.5

60


∑f = 20

∑fx = 730

∑fd = 40

Mean = A + ∑fd
∑f
Mean = 34.5 + 40
20
Mean = 34.5 + 2
Hence Mean = 36.5
Also you can prove your
answer by using the normal formula of calculating mean, that is ∑fx/∑f and try
to see if you get the same answer.
No comments:
Post a Comment