Browse Questions

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

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

Toolbox:
• 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 = $\large\frac{\sum x_i}{n}$
$\qquad=\large\frac{72}{8}$
$\qquad= 9$
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.