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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

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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