Probability

If the probability distribution of a random variable $X$ is as follows, then the mean of $X$ is

$$ \begin{array}{ccccc} \hline \boldsymbol{X}=\boldsymbol{x}_{\boldsymbol{i}} & -1 & 0 & 1 & 2 \\ \hline \boldsymbol{P}\left(\boldsymbol{X}=\boldsymbol{x}_{\boldsymbol{i}}\right) & \boldsymbol{k}^3 & 2 \boldsymbol{k}^3+\boldsymbol{k} & 4 \boldsymbol{k}-10 \boldsymbol{k}^2 & 4 \boldsymbol{k}-1 \\ \hline \end{array} $$