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Find the mean and variance for each of the data : $6,7,10,12,12,4,8,12$

$\begin{array}{1 1}(A)\;9.25\\(B)\;3\\(C)\;2\\(D)\;7\end{array} $

Can you answer this question?

1 Answer

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  • Formula to calculate mean and variance :
  • Mean = $\large\frac{\sum x_i}{n}$
  • variance =$\large\frac{\sum x_i^2}{n} - \bigg( \large\frac{\sum x_i}{n} \bigg)^2$
Step 2:
Mean = $\large\frac{\sum x_i}{n}$
$\qquad= 9$
Step 3:
variance =$\large\frac{\sum x_i^2}{n} - \bigg( \large\frac{\sum x_i}{n} \bigg)^2$
$\qquad= \large\frac{722}{8} =\bigg(\large\frac{72}{8})^2$
$\qquad= 90.25 -81=9.25$
Hence A is the correct answer.
answered Jun 26, 2014 by meena.p
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