Lesson 17: Distributions of Two Discrete Random Variables
As the title of the lesson suggests, in this lesson, we'll learn how to extend the concept of a probability distribution of one random variable X to a joint probability distribution of two random variables X and Y. In some cases, X and Y may both be discrete random variables. For example, suppose X denotes the number of significant others a randomly selected person has, and Y denotes the number of arguments the person has each week. We might want to know if there is a relationship between X and Y. Or, we might want to know the probability that X takes on a particular value x and Y takes on a particular value y. That is, we might want to know P(X = x , Y = y).
- To learn the formal definition of a joint probability mass function of two discrete random variables.
- To learn how to use a joint probability mass function to find the probability of a specific event.
- To learn how to find a marginal probability mass function of a discrete random variable X from the joint probability mass function