GCSE Maths Probability Revision Notes
Master GCSE Maths Probability using simple revision notes, key facts and practice questions — all generated by AI for your exam.
Probability is the measure of how likely an event is to occur. It is expressed as a number between 0 and 1, where 0 means the event cannot happen and 1 means it will definitely happen.
Key Concepts
- 1Probability is calculated as the number of successful outcomes divided by the total number of possible outcomes.
- 2The probability of an event is expressed as a fraction, decimal, or percentage.
- 3The sum of probabilities of all possible outcomes in a sample space equals 1.
- 4Independent events do not affect each other's probabilities.
- 5The complementary probability of an event is 1 minus the probability of the event occurring.
Simple Explanation
Probability tells us how likely something is to happen. If you have a bag with 3 red balls and 2 blue balls, the probability of picking a red ball is 3 out of 5, or 0.6. This means if you pick a ball at random, there's a 60% chance it will be red. We can write probabilities as fractions, decimals, or percentages.
Memory Trick
“Remember 'Probability is P/Total', where P is the number of successful outcomes and Total is the total number of outcomes.”
Flashcards
What is the probability of rolling a 3 on a standard die?
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Exam Questions
Describe and explain how to calculate the probability of an event occurring. [6 marks]
6 marksView mark scheme hint▾
Define probability, explain the formula, give examples, and state the range of probability values.
Explain how independent events affect the probability of combined events. [4 marks]
4 marksView mark scheme hint▾
Define independent events, explain how to calculate combined probabilities, and give an example.
What is meant by the term 'complementary probability'? [2 marks]
2 marksView mark scheme hint▾
Define complementary probability and give the formula for calculating it.
Practice Quiz
What is the probability of drawing an Ace from a standard deck of 52 cards?
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