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A Level Maths · Statistics · Year 12 and 13

A Level Maths Probability revision

Probability questions reward a good diagram. Venn diagrams, tree diagrams and two-way tables turn wordy questions into arithmetic; Year 13 adds conditional probability and set notation.

  • Same content for AQA, Edexcel and OCR
  • Step-by-step mark schemes
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Start with one question on probability. Stuck? Take a hint. No sign-in needed.

The probability that it rains tomorrow is \(\frac{7}{20}\). Find the probability that it does not rain.
Choose your answer · keys 1–4
What you need to know

Probability in Year 12 and Year 13

AS content is usually taught in Year 12. The full A Level adds the Year 13 content. Sitting AS exams or mocks? See the AS Level Maths checklist.

Year 12 (AS content)

  • Mutually exclusive and independent events
  • Venn diagrams, tree diagrams and two-way tables

Year 13 (full A Level only)

  • Conditional probability, including set notation P(A | B)
  • Modelling with probability and questioning the assumptions

Worked examplemedium3 marks

Given that $P(X) = 0.4$, $P(Y) = 0.5$, and $P(X \cap Y) = 0.2$, find the conditional probability $P(X | Y)$.

Mark scheme and worked answer
3 steps

Then practise: skills to practise · open probability practice questions.

Where it's examined

Probability on the AQA, Edexcel and OCR papers

Every board examines the same A Level Maths content, set by the Department for Education. Only the paper it appears on and the section numbering differ.

BoardSpecification referenceExamined in
AQA 7357AQA section MPaper 3
Edexcel 9MA0Edexcel topic Statistics 3Paper 3, Section A
OCR A H240OCR reference 2.03Paper 2, statistics section

Statistics questions can be set in the context of your board's large data set: large data set guides and practice (Edexcel · AQA · OCR A).

Practice questions

A Level Maths probability exam-style questions

Three examples from the question bank, one with its full mark scheme open. Every question comes with a step-by-step mark scheme (M, A and B marks) once you start practising.

Question 1easy2 marks

Events $A$ and $B$ are mutually exclusive. Given that $P(A) = 0.3$ and $P(B) = 0.45$, find $P(A \cup B)$.

Mark scheme: in the 7-day free trial.

Question 2medium3 marks

Given that $P(A) = 0.5$, $P(B) = 0.6$, and $P(A \cup B) = 0.85$, find $P(A \cap B)$.

Full worked solution Free, no sign-in

  1. M1 for using the general addition rule: $P(A \cup B) = P(A) + P(B) - P(A \cap B)$.
  2. M1 for substituting the known values: $0.85 = 0.5 + 0.6 - P(A \cap B)$.
  3. A1 for solving to find $P(A \cap B) = 1.1 - 0.85 = 0.25$.

Every question here has a full worked solution. See them all →

Question 3hard3 marks

The probability that it rains on a given day is $0.4$. If it rains, the probability that Alice takes the bus is $0.8$. If it does not rain, the probability that she takes the bus is $0.3$. Given that Alice takes the bus, find the probability that it rained that day.

Mark scheme: in the 7-day free trial.

Questions are original and written in the style of Edexcel 9MA0, and cover content that AQA and OCR examine too. They are not past-paper questions.

Full question sets with mark schemes: conditional probability questions (15)

Revision notes: Probability: Venn diagrams, trees and independence · Conditional probability and modelling

In the practice engine

Skills you can practise

These skills sit in the Statistics unit of the UK A Level practice engine. Pick any mix of them, set the difficulty, and check each answer against its mark scheme.

Basic probability & sample spaceVenn diagramsMutually exclusive & independent eventsConditional probabilityProbability tree diagramsTwo-way tables

Open Statistics practice

Past papers

Past paper questions on probability

Probability can come up on these papers (from each board's paper structure). We haven't mapped individual questions yet, so open a recent paper and look for it.

BoardRecent papers that can test it
Edexcel 9MA0Paper 3: June 2025, June 2024, June 2023
AQA 7357Paper 3: June 2025, June 2024, June 2023
OCR H240Paper 2: June 2025, June 2024, June 2023

Papers are © the exam boards; each page links to the official question paper and mark scheme. All A Level Maths past papers →

Probability: common questions

Is probability on the AQA, Edexcel and OCR A Level Maths exams?

Yes. Probability is part of the A Level Maths content that every board examines: AQA section M, Edexcel Statistics 3, OCR 2.03. It is assessed in AQA Paper 3; Edexcel Paper 3, Section A; OCR A Paper 2, statistics section.

Is probability Year 12 or Year 13 content?

Both. The AS content, usually taught in Year 12, is: Mutually exclusive and independent events; Venn diagrams, tree diagrams and two-way tables. The full A Level adds: Conditional probability, including set notation P(A | B); Modelling with probability and questioning the assumptions.

How do I show two events are independent?

Show that P(A ∩ B) = P(A) × P(B), or that P(A | B) = P(A). Say which one you are testing and write a conclusion.

Your probability revision kit

More A Level Maths statistics topics

Stretch yourself: original probability problems at Senior level (ages 16 to 18), with hints and full solutions: Problem S101 · Problem S29 · Problem S102 · Problem S30. All 20 →

More on this topic

Applying for maths, computer science or economics? TMUA practice on this topic: Statistics and probability. TMUA preparation: notes, questions and mock papers → Taking STEP? STEP-style problems: Probability and statistics.

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