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Find the Mean and Variance for the Following Frequency Distribution. 0-30 30-60 60-90 90-120 120-150 150-180 180-210 - Mathematics

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ConceptVariance and Standard Deviation Standard Deviation of a Discrete Frequency Distribution

Question

Find the mean and variance for the following frequency distribution.

Classes

0-30

30-60

60-90

90-120

120-150

150-180

180-210

Frequencies

2

3

5

10

3

5

2

Solution

Class Frequency fi Mid-point xi `y_i = (X_i-105)/30` yi2 fiyi fiyi2

0-30

2

15

–3

9

–6

18

30-60

3

45

–2

4

–6

12

60-90

5

75

–1

1

–5

5

90-120

10

105

0

0

0

0

120-150

3

135

1

1

3

3

150-180

5

165

2

4

10

20

180-210

2

195

3

9

6

18

 

30

     

2

76

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Solution Find the Mean and Variance for the Following Frequency Distribution. 0-30 30-60 60-90 90-120 120-150 150-180 180-210 Concept: Variance and Standard Deviation - Standard Deviation of a Discrete Frequency Distribution.
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