Answer:
They all add up to 1
Explanation:
For a given probability model, when we add all possible probabilities, our answer must be equal to 1.
In a probability model, what we are trying to do is to look at all possible outcomes that can arise from using the model. All these outcomes can be seen as a fraction of the total. They each have their own percentage of occurrence.
It is when we are up all these fractions that we can get the maximum which must not be greater than 1. Thus, all probabilities of occurrence in a probability model ranges from 0 to 1, with the addition of all the probabilities equal to 1. 0 being the probability that the intended event has no probability of occurrence at all and 1 meaning it has the maximum possible probability to occur