For a set of observations,if the coefficient of variation is $25$ and the mean is $44$,then the variance is:

If the mean of the data $7, 8, 9, 7, 8, 7, \lambda, 8$ is $8$,then the variance of the data is:

The variance of the following continuous frequency distribution is
$\begin{array}{|l|c|c|c|c|}\hline \text{Class interval} & 0-4 & 4-8 & 8-12 & 12-16 \\ \hline \text{Frequency} & 2 & 3 & 2 & 1 \\ \hline\end{array}$

If for a distribution $\Sigma(x-5)=3$,$\Sigma(x-5)^{2}=43$ and the total number of items is $18$,find the mean and standard deviation.

If the variance of the numbers $-1, 0, 1, k$ is $5$,where $k > 0$,then $k$ is equal to

Find the mean and variance for the following data:

$x_i$	$6$	$10$	$14$	$18$	$24$	$28$	$30$
$f_i$	$2$	$4$	$7$	$12$	$8$	$4$	$3$