Skip to content
Know.itKnow.it
Create an animated lesson
On request

This article is free to read. Creating a lesson uses your daily or stored credits; review the language and settings before starting.

What is probability?

MathematicsLesson on requestFree to read

Quick answer

Probability is the branch of math that measures how likely an event is, on a scale from 0 (impossible) to 1 (certain). It's how we reason about chance, risk, and uncertainty. When outcomes are equally likely, probability = favorable outcomes ÷ total outcomes.

Key things to understand

  1. When outcomes are equally likely, probability = favorable outcomes ÷ total outcomes.
  2. It ranges from 0 (never) to 1 (always); 0.5 means 50-50.
  3. Independent events' probabilities multiply (e.g., two coin flips).
  4. It underpins statistics, gambling odds, insurance, and machine learning.

People also ask

How do you calculate simple probability?
Divide the number of favorable outcomes by the total number of equally likely outcomes.
What does a probability of 0.5 mean?
A 50% chance — the event is as likely to happen as not, like a fair coin landing heads.
What's the difference between probability and statistics?
Probability predicts the chance of outcomes; statistics analyzes real data to draw conclusions.