What is Probability?

Pre-Algebra · Axiom Academy

How a single number between 0 and 1 captures exactly how likely an event is to happen. 1. What Does Probability Measure? A probability is a single number that says how likely an event is. The more likely the event, the larger the number — and it always lands between two fixed ends: an impossible event sits at 0 , a certain event at 1 , and everything else somewhere in between. P=0 means it cannot happen; P=1 means it is sure to happen. 2. The Probability Number Line Because every probability is a number from 0 to 1 , we can lay them all out on a single number line . An event's likelihood is just a position on that line: slide toward 1 as it grows more likely, toward 0 as it grows less likely. 3. Real-World Events on the Scale Watch where everyday events land. Each one drops onto the spot that matches its likelihood — impossible events pile up at 0 , near-sure ones crowd toward 1 , and an even chance sits dead center. You've seen how a single number from 0 to 1 captures the likelihood of any event, and how to read real events off that scale. Scroll up to revisit any step.

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