# 6.11: Introduction to Probability Rules

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## What you’ll learn to do: Reason from probability distributions, using probability rules, to answer probability questions.

In this section, we introduce probability rules and properties. These rules can make evaluating probabilities far simpler and can also help catch mistakes if results are nonsensical (for example, a 140% chance is impossible). We revisit conditional probabilities, which are a fundamental concept in understanding how to interpret results from hypothesis testing. Finally, we introduce the notion of independence, joint, and marginal probabilities, and present a useful rule that ties these concepts together.  