Year 11 - Maths
Combinations
Conditional probability
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This pupil-friendly study guide includes a unit summary, clear notes, common mistakes, and quick questions with answers.
Unit Summary
In this unit, pupils use their knowledge of calculating theoretical probabilities and extend it to calculate conditional probabilities.
Lesson Summary
You will learn to derive the product rule for counting, including when to divide by 2.
Key Notes
- By systematically listing the outcomes for two or more events, a pattern begins to emerge
- This pattern can be generalised so that counting possible outcome combinations is quicker
- Whether the order of the outcomes matters affects the number of possible outcomes
- If order does not matter then repetition can be accounted for when considering the total number of outcomes
Vocabulary To Learn
- Trial: A trial is a single, predefined test.
- Outcome: An outcome is a result of a trial.
- Systematically: When listing outcomes systematically, they are listed in such a way as to ensure all outcomes are recorded.
Common Mistakes To Avoid
- When using the product rule, pupils may be unsure whether they should divide the product by 2.
3 Quick Questions (With Answers)
1. Solve this in steps: explain the method from this lesson and why each step matters.
By systematically listing the outcomes for two or more events, a pattern begins to emerge. This pattern can be generalised so that counting possible outcome combinations is quicker.
2. Use this key word in a maths sentence and explain it clearly. 'Trial'
A trial is a single, predefined test. Use this word when showing your method, then check your final answer is reasonable.
3. Spot and fix this common maths mistake.
Mistake: When using the product rule, pupils may be unsure whether they should divide the product by 2. Correction: Pay extra attention to the context of the problem. If the order of the two outcomes is irrelevant, then you should divide by two. If each of the two outcomes is allocated to a separate event (e.g. 1st and 2nd) then do not divide by 2.
More Lessons In This Unit
- Advanced problem solving with conditional probability Study Guide
- Algebra in tree and Venn diagrams Study Guide
- Checking and securing calculating probabilities from diagrams Study Guide
- Checking and securing calculating probabilities from tables Study Guide
- Checking and securing displaying outcomes Study Guide
- Checking and securing exhaustive events Study Guide
- Comparing multiple representations to calculate conditional probabilities Study Guide
- Conditional probability in a tree diagram Study Guide
- Conditional probability in a two-way table Study Guide
- Conditional probability in a Venn diagram Study Guide
- Constructing three event Venn diagrams Study Guide
- Experimental probability Study Guide
- Experimental vs theoretical probability Study Guide
- Frequency trees Study Guide
- Probabilities in three event Venn diagrams Study Guide
- Probabilities involving algebra Study Guide
- Problem solving with conditional probability Study Guide
- Set notation Study Guide
Browse all guides in the Year 11 Maths guide library.