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This topic covers the probability scale, calculating the probability of a single event as favourable ÷ total outcomes, and that probabilities sum to 1. It's examined right across GCSE and iGCSE Maths. Work through it free on eClassroom, with clear worked examples and instantly-marked questions that build your confidence for the exam.
How you do it
Probability is the number of ways the event can happen divided by the total number of equally likely outcomes. All the probabilities of a complete set of outcomes add to 1, so the chance of something not happening is 1 minus the chance that it does.
Before you start
Best tackled after fractions and decimals. You meet it at Foundation and Higher tier. Later work on combined events and tree diagrams assumes it.
What you learn
Every probability is a number from 0 (impossible) to 1 (certain), with 1 ⁄ 2 an even chance. For one experiment, the probabilities of all possible outcomes add up to 1. A probability can be written as a fraction, decimal or percentage — all the same thing. The course works through the probability scale and counting outcomes, probabilities add up to 1 and fractions, decimals and percentages. Every section has instant-feedback practice questions matched to Edexcel iGCSE 4MA1 and the other major GCSE boards, and the course finishes with full exam-style questions you mark yourself.
Related Topics
In our GCSE maths courses, Basic Probability belongs to Probability and is met in Foundation tier. You work through 3 concepts and 2 worked examples, testing yourself at 3 points. Nearby topics in the same strand are Conditional Probability, Expected Frequency and Mutually Exclusive Events. The Probability revision engine gives you as many extra questions as you want, tracked on your skill tree.
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