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 quantifies uncertainty and helps us make informed decisions based on the chances of various outcomes.
Key Concepts
- 1Probability ranges from 0 (impossible event) to 1 (certain event).
- 2The sum of probabilities of all possible outcomes of a random experiment equals 1.
- 3Independent events have probabilities that do not affect each other.
- 4Conditional probability measures the likelihood of an event given that another event has occurred.
- 5The Law of Total Probability and Bayes' theorem are key concepts in calculating probabilities.
Simple Explanation
Probability is all about figuring out how likely something is to happen. If something has a probability of 0, it will never happen, and if it has a probability of 1, it will definitely happen. For example, flipping a fair coin has a 50% chance of landing on heads or tails. We can use probability to predict outcomes in games, weather, and many other situations.
Memory Trick
“Think of probability as a scale from 0 to 1, where 0 means 'no chance' and 1 means 'certain.' You can remember it with the phrase '0 to 1, chance is fun!'”
Flashcards
What is the probability of an impossible event?
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Exam Questions
Describe and explain the Law of Total Probability and its applications. [6 marks]
6 marksView mark scheme hint▾
Define the law, provide an example, and explain its significance in calculating probabilities.
Explain how conditional probability is used in real-life situations. [4 marks]
4 marksView mark scheme hint▾
Define conditional probability and give at least one practical example.
What is meant by independent events in probability? [2 marks]
2 marksView mark scheme hint▾
Define independent events and provide a brief example.
Practice Quiz
What is the probability of rolling a 3 on a fair six-sided die?
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