Q.1. Calculate mean , standard deviation and variance :

Variable : 0-5 5-10 10-15 15-20 20-25 25-30 30-35 35-40

frequency : 2 5 7 13 21 16 8 3

Q.2. The number examined , the meanweight and standard deviation in each group of examination by two medical examiners are given below . calculate mean and standard deviation of both the group taken together .

Medical examiner number examined mean weight (lbs) standard deviation (lbs)

A 50 113 6.5

B 60 120 8.2

Q.3. You are given the following data about height of boys and girls :

Boys Girls

Number 72 38

Average height (in inches) 68 61

Variance of distribution (in inches) 9 4

(a) calculate cofficient of variation

(b) decide whose height is more variable .

Solution 1

X

f

m

fm


 


 

0-5

2

2.5

5

6.25

12.5

5-10

5

7.5

37.5

56.25

281.25

10-15

7

12.5

87.5

156.25

1093.75

15-20

13

17.5

227.5

306.25

3981.25

20-25

21

22.5

472.5

506.25

10631.25

25-30

16

27.5

440

756.25

12100

30-35

8

32.5

260

1056.25

8450

35-40

3

37.5

112.5

1406.25

4218.75


 


 


 


 


 


 

 

Solution 3


 

Boys

Girls

Number

72

38

Average Height

68

61

Variance of Distribution


 

9

4

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