The possible values of $x$ if the standard deviation $(SD)$ of the numbers $2, 3, 2x$,and $11$ is $3.5$ are equal to:

The mean and variance of the observations $x_1, x_2, x_3, \ldots, x_{15}$ are respectively $2$ and $4$. If the mean and variance of the observations $y_1, y_2, \ldots, y_{10}$ are respectively $2$ and $5$,then the variance of the combined observations $x_1, x_2, \ldots, x_{15}, y_1, y_2, \ldots, y_{10}$ is

The mean of $5$ numbers is $18$. If one number is excluded,their mean becomes $16$. Then the excluded number is

Consider the frequency distribution of the given numbers. If the mean is known to be $3$,then the value of $f$ is:

Value	$1$	$2$	$3$	$4$
Frequency	$5$	$4$	$6$	$f$

The mean and variance of a set of $6$ terms are $11$ and $24$ respectively,and the mean and variance of another set of $3$ terms are $14$ and $36$ respectively. Then,the variance of all $9$ terms is equal to:

If the variance of the data $2, 3, 5, 8, 12$ is $\sigma^2$ and the mean deviation from the median for this data is $M$,then $\sigma^2 - M =$