Unit 9 Summary

Pre-Algebra · Axiom Academy

SUMMARY Probability and Chance A review of how probability puts a number on uncertainty — and how that lets us make better decisions in an unpredictable world. Patterns live inside randomness. A single outcome is unpredictable, but over many trials the long-run behavior is remarkably stable. Unlikely is not impossible. A low probability still happens sometimes — never read "rare" as "can't occur." More trials, sharper estimate. The more you repeat an experiment, the closer experimental probability creeps toward the theoretical value. Probability is a decision tool. It lets you weigh options and assess risk rationally when the outcome is genuinely uncertain. One idea, three faces. Fluently converting between fractions, decimals, and percents keeps you flexible — . Core Concept Probability as a Number Probability is a single number measuring how likely an event is. 0 means impossible, 0.5 means an even chance, and 1 means certain — everything else sits in between. Three forms: the same value as a fraction, decimal, or percent ( ). Watch out for: a probability can never be negative or above 1 — if you get one, recheck the count. Core Concept Theoretical vs. Experimental Theoretical probability is counted from the equally-likely outcomes; experimental probability is measured from real trials. The Law of Large Numbers says the experimental value drifts toward the theoretical one as trials pile up. When to use experimental: when outcomes aren't equally likely or the math is hard.

This is the written version of the interactive lesson above. See the full Pre-Algebra course.