Question

Which of the following condition should be satisfied by function for pmf?

(a) The sum of all of the possible values is 1

(b) The sum of all of the possible values is 0

(c) The sum of all of the possible values is infinite

(d) All of the mentioned

This question was posed to me by my college professor while I was bunking the class.

I want to ask this question from Introduction to Statistical Inference topic in division Statistical Inference and Regression Models of Data Science

Answer 1

Correct choice is (a) The sum of all of the possible values is 1

To explain I would say: A probability mass function evaluated at a value corresponds to the probability that a random variable takes that value.