Find the mean of the following distribution by step ...

ICSE Class X Math 2013 Solved Paper

© examsnet.com

Question : 37

Total: 46

Find the mean of the following distribution by step deviation method:

Class Interval	20-30	30-40	40-50	50-60	60-70	70-80
Frequency	10	6	8	12	5	9

Solution:

C.I.

Frequency (fi)

Mid-value(x)

di=‌

x−a

h

fidi

20-30

10

25

-2

-20

30-40

6

35

-1

-6

40-50

8

45

0

0

50-60

12

55

1

12

60-70

5

65

2

10

70-80

9

75

3

27

Σfi=50

Σfidi=50

Here, a=45 and h=10
∴‌‌‌ Mean ‌=a+‌

Σfidi

Σfi

×h
‌=45+‌

23

50

×10
‌=45+4.6=49.6

© examsnet.com

Go to Question:

Prev Question

Next Question