Answer
1) The summation of all probabilities must be equal to 1.
2) Each probability must be a number greater than or equal to 0 and less than or equal to 1.
Work Step by Step
One of the possible results for the random variable X must occur with 100% of certainty. So, $ΣP(x)=1$.
Any of the possible results for the random variable X must have a probability greater than or equal to 0 and less than or equal to 1, that is, $0\leq P(x)\leq1$.
