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This topic covers the addition ('OR') and multiplication ('AND') rules of probability — adding for mutually exclusive events and multiplying for independent events. 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
When both events happen, multiply their probabilities. When either can happen and they cannot occur together, add them. The word AND signals multiply and OR signals add — mixing them up is the single most common probability error.
Before you start
Bring basic probability and fractions with you. This is a Foundation and Higher tier topic. From here the path runs to tree diagrams and conditional probability.
What you learn
Two events are independent if one does not affect the other (e.g. Then the overlap is 0 and this becomes simply P(A) + P(B). The course works through independent events and the AND rule, the OR rule (with overlap) and independent or mutually exclusive?. 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
And / OR rules is a Probability topic in the GCSE syllabus, covered here at Higher tier. The course is built from 3 concept sections, 2 worked examples and 3 check points before the exam-style set. It sits alongside Basic Probability, Conditional Probability, Expected Frequency and Mutually Exclusive Events in the same strand. For unlimited practice, the Probability revision engine builds new questions on demand and records your accuracy.
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