If the standard deviation of $x_i$ is $10$,what will be the variance of $(50 + 5x_i)$?

If the standard deviation of the numbers $-1, 0, 1, k$ is $\sqrt{5}$ where $k > 0$,then $k$ is equal to

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.

The mean of four observations is $3$. If the sum of the squares of these observations is $48$,then their standard deviation is

Let $\sigma_1$ and $\sigma_2$ be the standard deviations of two distributions $D_1$ and $D_2$ respectively,and $D_1$ be more consistent than $D_2$. If the means of $D_1$ and $D_2$ are the same,then the percentage increase in the standard deviation of $D_2$ over the standard deviation of $D_1$ is:

If the variance of the frequency distribution is $160$,then the value of $c \in N$ is

$X$	$c$	$2c$	$3c$	$4c$	$5c$	$6c$
$f$	$2$	$1$	$1$	$1$	$1$	$1$