Question

1) Calculate standard deviation and its coefficient By
Actual mean method.
Marks
0-4
4-8
8-12
12-16
Frequency
4, 8, 2, 1

Answer 1

Answer:

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Class 11

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>>Calculate the Standard Deviation and coe

Question

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Calculate the Standard Deviation and coefficient of variation for the given frequency table:

Class-interval Frequency

1−5 1

6−10 2

11−15 3

16−20 4

Medium

Solution

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C.I f Mid point x fx D=X−

X

D

2

fD

2

1−5 1 3 3 −10 100 100

6−10 2 8 16 −5 25 50

11−15 3 13 39 0 0 0

16−20 4 18 72 +5 25 100

N=10

∑fx=130

∑fD

2

=250

Standard Deviation =σ=

N

∑fD

2

=

10

250

=

25

Therefore, σ=5

Coefficient of variation, C.V=

x

σ

×100=

13

5

×100=

13

500

=38.46