Find the mean and variance for the following frequency distribution

$\begin{matrix} Classes & 0 - 30 & 30 - 60 & 60 - 90 & 90 - 120 & 120 - 150 & 150 - 180 & 180 - 210 Frequency & 2 & 3 & 5 & 10 & 3 & 5 & 2 \end{matrix}$

Or

The mean and standard deviation of six observations are 8 and 4, respectively. If each observation is multiplied by 3, find the mean and new standard deviation of the resulting observations.

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Solution

Mean = 107, Variance = 2276

Or

Mean = 24 and SD = 12

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Calculate mean, variance and standard deviation for the following frequency distribution:

$\begin{matrix} Class & 0 - 30 & 30 - 60 & 60 - 90 & 90 - 120 & 120 - 150 & 150 - 180 & 180 - 210 Frequency & 2 & 3 & 5 & 10 & 3 & 5 & 2 \end{matrix}$

The mean and standard deviation of six observations are 8 and 4, respectively. If each observation is multiplied by 3, find the new mean and new standard deviation of the resulting observations.

Calculate the standard deviation for the following data :

$\begin{matrix} C l a s s : & 0 - 30 & 30 - 60 & 60 - 90 & 90 - 120 & 120 - 150 & 150 - 180 & 180 - 210 F r e q u e n c y : & 9 & 17 & 43 & 82 & 81 & 44 & 24 \end{matrix}$

Q. Calculate the standard deviation for the following data:

Class:	0-30	30-60	60-90	90-120	120-150	150-180	180-210
Frequency:	9	17	43	82	81	44	24

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

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Mean = 107, Variance = 2276 Or Mean = 24 and SD = 12

Mean = 107, Variance = 2276

Or

Mean = 24 and SD = 12