Probability Basics (Edexcel GCSE Maths): Flashcards

How likely something is to happen

Between $0$ and $1$

Impossible - will never happen

Certain - will definitely happen

As likely as not (50-50 chance)

Favourable outcomes ÷ total outcomes

When all outcomes are equally likely

Fair or at random

Must equal $1$

Pairs where one or other happens, but not both

$P(\text{event}) + P(\text{not event}) = 1$

Subtract known probabilities from $1$