IGCSE Maths / Probability

At least one, and the complement revision notes

Edexcel International GCSE Maths (4MA1), chapter 20: Probability, specification point 6.3b. Part of the full course.

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“At least one” means one or more events happen. It is often quickest to find the probability that none happen, then subtract that from 1.

More lessons in Probability

• The language of probability and the probability scale
• Listing outcomes systematically
• Theoretical probability and sample space
• Relative frequency and mutually exclusive events
• Expected frequency and relative frequency
• Multiplying independent probabilities
• Tree diagrams with replacement
• Tree diagrams without replacement
• Three stage tree diagrams
• Probability problem solving
• Conditional probability from a two way table
• Conditional probability from a Venn diagram
• Conditional probability without replacement
• Forming an equation from a probability