A-LevelMaths

A-Level Maths Probability Revision Notes

Master A-Level Maths Probability using simple revision notes, key facts and practice questions — all generated by AI for your exam.

Probability is a branch of mathematics that deals with the likelihood of events occurring. It provides a framework for quantifying uncertainty and making informed decisions based on data.

Key Concepts

  • 1Probability ranges from 0 (impossible event) to 1 (certain event).
  • 2The sum of probabilities of all possible outcomes in a sample space is 1.
  • 3Independent events occur when the outcome of one event does not affect the other.
  • 4Conditional probability measures the probability of an event given that another event has occurred.
  • 5The law of total probability and Bayes' theorem are key concepts for calculating probabilities in complex scenarios.

Simple Explanation

Probability helps us understand how likely something is to happen. It is expressed as a number between 0 and 1, where 0 means it will never happen and 1 means it will definitely happen. For example, if you flip a coin, the probability of getting heads is 0.5 because there are two equally likely outcomes: heads or tails.

Memory Trick

Remember 'P(0-1)' for Probability: P stands for Probability, and the numbers 0 and 1 remind you that probability values range from 0 (impossible) to 1 (certain).

Flashcards

Question1 / 5

What is the probability of an event that is certain?

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Exam Questions

Describe and explain the concept of conditional probability and provide an example. [6 marks]

6 marks
View mark scheme hint

Define conditional probability, explain its formula, and give a relevant example with calculations.

Explain how the law of total probability can be applied in a given scenario. [4 marks]

4 marks
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State the law, illustrate with a scenario, and show how to calculate total probability.

What is meant by independent events in probability? [2 marks]

2 marks
View mark scheme hint

Define independent events and provide a brief example.

Practice Quiz

Question 1 of 5Score: 0

What is the probability of rolling a 3 on a fair six-sided die?

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