Calculate the sample mean and sample variance for the following frequency distribution of heights in centimeters for a sample of 8-year-old boys. If necessary, round to one more decimal place than the largest number of decimal places given in the data.
Heights in Centimeters
Class Frequency
121.6-125.2 31125.3-128.9 46129.0-132.6 40132.7-136.3 46136.4-140.0 19

And the variance can be calculated with this formula:

And replacing we got:

Step-by-step explanation:

For this case we can calculate the mean with the following table:

Class                Midpoint (xi)    fi         xi *fi        xi^2 *fi

121.6- 125.2          123.4           31       3825.4      472054.36

125.3-128.9          127.1            46      5846.6      743102.86

129.0-132.6          130.8           40      5232         684345.6

132.7-136.3          134.5           46      6187          832151.5

136.4-140.0          138.2           19      2625.8      362885.56

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Total                                       182      23716.8      3094539.88

And we can calculate the mean with the following formula

And the variance can be calculated with this formula:

And replacing we got:

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step-by-step explanation:

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step-by-step explanation: