Lesson 3: Probability Distributions

Overview Section

In this Lesson, we take the next step toward inference. In Lesson 2, we introduced events and probability properties. In this Lesson, we will learn how to numerically quantify the outcomes into a random variable. Then we will use the random variable to create mathematical functions to find probabilities of the random variable.

One of the most important discrete random variables is the binomial distribution and the most important continuous random variable is the normal distribution. They will both be discussed in this lesson. We will also talk about how to compute the probabilities for these two variables.


Upon successful completion of this lesson, you should be able to:

  • Distinguish between discrete and continuous random variables.
  • Compute probabilities, cumulative probabilities, means and variances for discrete random variables.
  • Identify binomial random variables and their characteristics.
  • Calculate probabilities of binomial random variables.
  • Describe the properties of the normal distribution.
  • Find probabilities and percentiles of any normal distribution.
  • Apply the Empirical rule.