# Chapter 6: Discrete Probability Distributions

Source: Wikipedia

In Chapter 6, we expand on the probability concepts we learned in Chapter 5, and introduce the idea of a **random variable**. Random variables are useful because they help us determine if playing a game like roulette (shown to the right) is profitable in the long-term. (It isn't.)

Random variables also help us determine how insurance companies set the premiums for their policies. They can also help an investor decide whether or not to invest in a company.

Source: stock.xchng

In Section 6.2, we'll introduce a specific type of random variable called a** binomial random variable**. Binomial random variables will help us answer questions like "What's the probability of getting 3 questions right on a multiple choice test if we're just guessing?" Or "If a basketball player makes 80% of her free throws, how often will she make less than 8 of 10?"

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