The sum of $10$ values is $12$ and the sum of their squares is $16.9$,then their standard deviation $(S.D.)$ is

If the standard deviation of the numbers $2, 3, a$,and $11$ is $3.5$,then which of the following is true?

If $1$ is added to each of the first $10$ natural numbers,then the variance of the numbers so obtained is:

If the mean of the numbers $a, b, 8, 5, 10$ is $6$ and the variance is $6.80$,then which of the following is a possible value for $a$ and $b$?

The variance of $10$ observations is $16$. If each observation is doubled,then the standard deviation of the new data will be -

Two teams $A$ and $B$ have the same mean and their coefficients of variation are $4$ and $2$,respectively. If $\sigma_A$ and $\sigma_B$ are the standard deviations of teams $A$ and $B$ respectively,then the relation between them is