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.
- $$\begin{array} { c | c } \mathrm { x } & \mathrm { P } ( \mathrm { x } ) \\\hline 0 & 0.15 \\1 & 0.33 \\2 & 0.22 \\3 & 0.28 \\4 & 0.02\end{array}$$