Answer:
Sum of probabilities in a discrete probability distribution is 1.
Explanation:
The sum of the probabilities in a probability distribution is always 1. 
 
A probability distribution is a collection of probabilities that defines the likelihood of observing all of the various outcomes of an event or experiment. Based on this definition, a probability distribution has two important properties that are always true: 
 
Each probability in the distribution must be of a value between 0 and 1. 
The sum of all the probabilities in the distribution must be equal to 1.