The mean deviation from the mean of the discrete data $2,3,5,7,11,13,17,19,22$ is

The probability distribution of a random variable $X$ is given below. Then, the standard deviation of $X$ is

$$ \begin{array}{llllll} \hline \boldsymbol{X}=\boldsymbol{x}_1 & 2 & 3 & 5 & 7 & 12 \\ \hline \boldsymbol{P}\left(\boldsymbol{X}=\boldsymbol{x}_1\right) & 3 k & k & k & 2 k & k \\ \hline \end{array} $$

The variance of the discrete data $3,4,5,6,7,8,10,13$ is

If a possion variate $X$ satisfies the relation $P(X=3)=P(X=5)$, then $P(X=4)=$