GCSE Maths: Basic Probability
Practise GCSE Maths probability — listing outcomes, the probability scale, mutually exclusive and independent events. AQA, Edexcel, OCR and Eduqas.
ProbabilityFoundation & HigherAQA · Edexcel · OCR · Eduqas
What you need to know
The concepts examiners test on basic probability, and what each one is really asking.
Probability scale (0 to 1)
P(event) = favourable outcomes / total outcomes
Mutually exclusive events: P(A or B) = P(A) + P(B)
Independent events: P(A and B) = P(A) × P(B)
Expected frequency
Where marks get lost
The exam technique that separates a correct method from a correct answer.
- Probabilities must sum to 1 for all mutually exclusive outcomes
- P(not A) = 1 − P(A)
- For "and" with independent events, multiply; for "or" with mutually exclusive events, add
Basic Probability questions students ask
What are mutually exclusive events?
Two events are mutually exclusive if they cannot both happen at the same time. If A and B are mutually exclusive, P(A or B) = P(A) + P(B).
What are independent events?
Two events are independent if the outcome of one does not affect the other. If independent, P(A and B) = P(A) × P(B).