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A Level Maths · Statistics · Year 12 and 13

A Level Maths Statistical Distributions revision

Statistical distributions covers the binomial distribution in Year 12 and the normal distribution in Year 13. Knowing when each model is appropriate matters as much as using the calculator functions.

  • Same content for AQA, Edexcel and OCR
  • Step-by-step mark schemes
  • 48-hour free trial, no card
What you need to know

Statistical Distributions in Year 12 and Year 13

AS content is usually taught in Year 12. The full A Level adds the Year 13 content.

Year 12 (AS content)

  • Discrete probability distributions
  • The binomial distribution B(n, p): conditions, probabilities and cumulative probabilities

Year 13 (full A Level only)

  • The normal distribution N(μ, σ²): properties, finding probabilities and unknown μ or σ
  • Using the normal distribution to approximate the binomial
  • Choosing a suitable distribution and judging the model

Worked examplemedium3 marks

The cumulative distribution function $F(x)$ for a discrete random variable $X$ is given by $F(1) = 0.2$, $F(2) = 0.7$, and $F(3) = 1$. Find $P(X=2)$.

Mark scheme and worked answer
  1. M1 for knowing the relationship $P(X=2) = F(2) - F(1)$.
  2. M1 for substituting the values: $0.7 - 0.2$.
  3. A1 for stating the probability is $0.5$.

Then practise: skills to practise · open statistical distributions practice questions.

Where it's examined

Statistical Distributions 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 NPaper 3, Section B
Edexcel 9MA0Edexcel topic Statistics 4Paper 3, Section A
OCR A H240OCR reference 2.04Paper 2, statistics section
Practice questions

A Level Maths statistical distributions exam-style questions

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

Question 1easy2 marks

The discrete random variable $X$ has a probability distribution given by $P(X=1)=0.1$, $P(X=2)=0.3$, $P(X=3)=k$, and $P(X=4)=0.2$. Find the value of $k$.

Mark scheme: in the 48-hour free trial.

Question 2medium3 marks

The random variable $X$ has probability function $P(X=x) = cx$ for $x = 1, 2, 3, 4$. Find the value of the constant $c$.

Mark scheme: in the 48-hour free trial.

Question 3hard4 marks

Two independent observations, $X_1$ and $X_2$, are taken from a discrete random variable $X$ with distribution $P(X=1)=0.2$, $P(X=2)=0.5$, and $P(X=3)=0.3$. Find $P(X_1 + X_2 = 4)$.

Mark scheme: in the 48-hour 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.

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.

Discrete random variables & distributionsThe binomial distributionBinomial cumulative probabilitiesThe normal distributionStandardising & z-valuesNormal approximation to the binomial

Open Statistics practice

Past papers

Past paper questions on statistical distributions

Statistical distributions 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 2024, June 2023, June 2022
AQA 7357Paper 3: June 2023, June 2022, November 2021
OCR H240Paper 2: June 2024, June 2023, June 2022

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

Statistical Distributions: common questions

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

Yes. Statistical Distributions is part of the A Level Maths content that every board examines: AQA section N, Edexcel Statistics 4, OCR 2.04. It is assessed in AQA Paper 3, Section B; Edexcel Paper 3, Section A; OCR A Paper 2, statistics section.

Is statistical distributions Year 12 or Year 13 content?

Both. The AS content, usually taught in Year 12, is: Discrete probability distributions; The binomial distribution B(n, p): conditions, probabilities and cumulative probabilities. The full A Level adds: The normal distribution N(μ, σ²): properties, finding probabilities and unknown μ or σ; Using the normal distribution to approximate the binomial; Choosing a suitable distribution and judging the model.

When can a binomial distribution be used?

When there is a fixed number of independent trials, each with two outcomes and the same probability of success. State these conditions in context when a question asks you to justify the model.

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