Determine Whether the Following Is a Probability Distribution

Short Answer

Determine whether the following is a probability distribution. If not, identify the requirement
that is not satisfied.
$\begin{array} { c | r } \boldsymbol { x } & \boldsymbol { P } ( \boldsymbol { x } ) \\\hline 0 & 0.1296 \\1 & 0.3456 \\2 & 0.3456 \\3 & 0.1536 \\4 & 0.0256\end{array}$