Probability — Edexcel GCSE Mathematics
In summary: Probability is a key topic in Edexcel GCSE Mathematics. Key exam tip: Always check that the sum of probabilities for all possible outcomes equals 1
Exam Tips for Probability
- Always check that the sum of probabilities for all possible outcomes equals 1
- Use a tree diagram for multi-stage experiments to keep track of probabilities
- Clearly label all branches and outcomes on tree diagrams
- When working with 'at least one' problems, consider calculating the complement (1 minus the probability of none)
- Read the question carefully to determine if events are independent or dependent
Common Mistakes
- Confusing independent and dependent events when calculating combined probabilities
- Failing to account for the 'without replacement' condition in dependent events
- Incorrectly summing probabilities that are not mutually exclusive
- Misinterpreting the sample space in complex Venn diagram problems
- Errors in arithmetic when calculating probabilities from frequency trees
Marking Points
- Correct use of the 0-1 probability scale
- Sum of probabilities for exhaustive and mutually exclusive events equals 1
- Systematic enumeration of outcomes using grids or tables
- Correct construction and interpretation of tree diagrams for combined events
- Correct application of conditional probability using two-way tables or tree diagrams
- Clear communication of assumptions made in probability models
📖 Read the full Probability Study Guide
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