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 a measure of how likely an event is to occur, expressed as a number between 0 and 1. A probability of 0 means the event will not happen, while a probability of 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.
- 2Probabilities can be expressed as fractions, decimals, or percentages.
- 3The sum of all probabilities in a sample space equals 1.
- 4Events can be independent or dependent, affecting how probabilities are calculated.
- 5Complementary events are those that cover all possible outcomes, where the probability of an event and its complement adds up to 1.
Simple Explanation
Probability tells us how likely something is to happen. For example, if you have a bag of 10 marbles, and 3 are red, the probability of picking a red marble is 3 out of 10. This means if you picked a marble many times, about 3 out of every 10 picks would be red. You can write probabilities as fractions, decimals, or percentages.
Memory Trick
“Remember the acronym 'P.O.P.' which stands for Probability = Outcomes / Possibilities.”
Flashcards
What is the probability of rolling a 3 on a fair six-sided 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, show the formula, provide examples, explain independent and dependent events.
Explain how complementary events work in probability. [4 marks]
4 marksView mark scheme hint▾
Define complementary events, give examples, explain their relationship to total probability.
What is meant by 'independent events' in probability? [2 marks]
2 marksView mark scheme hint▾
Define independent events and provide an example.
Practice Quiz
What is the probability of drawing an Ace from a standard deck of cards?
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