In this section, we'll extend many of the definitions and concepts that we learned there to the case in which we have two random variables, say X and Y. More specifically, we will:
• extend the definition of a probability distribution of one random variable to the joint probability distribution of two random variables
• learn how to use the correlation coefficient as a way of quantifying the extent to which two random variables are linearly related
• extend the definition of the conditional probability of events in order to find the conditional probability distribution of a random variable X given that Y has occurred
