Year 9 - Maths
Equally likely outcomes
Probability: possible outcomes
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This pupil-friendly study guide includes a unit summary, clear notes, common mistakes, and quick questions with answers.
Unit Summary
This unit introduces and explores the concept of liklihood as a relative measure, and demonstrates multiple ways to represent likelihood such as Venn diagrams, tree diagrams and two-way tables.
Lesson Summary
You will learn to state when outcomes will be equally likely.
Key Notes
- A set of possible outcomes can be stated.
- Outcomes can be evaluated to decide how likely they are.
- Outcomes with the same likelihood can be identified.
Vocabulary To Learn
- Outcome: An outcome is a result of a trial.
- Likelihood: Likelihood describes the chance that a particular event will occur.
- Trial: A trial is a single predefined test.
- Sample space: A sample space is all the possible outcomes of a trial. A sample space diagram is a systematic way of producing a sample space.
Common Mistakes To Avoid
- Rolling a 6 on a dice is less likely to happen than rolling other numbers. Or ticket 001 is less likely to be drawn in a raffle than other tickets.
3 Quick Questions (With Answers)
1. Solve this in steps: explain the method from this lesson and why each step matters.
A set of possible outcomes can be stated. Outcomes can be evaluated to decide how likely they are.
2. Use this key word in a maths sentence and explain it clearly. 'Outcome'
An outcome is a result of a trial. Use this word when showing your method, then check your final answer is reasonable.
3. Spot and fix this common maths mistake.
Mistake: Rolling a 6 on a dice is less likely to happen than rolling other numbers. Or ticket 001 is less likely to be drawn in a raffle than other tickets. Correction: The random nature of picking a raffle or rolling a dice means all outcomes are equally likely as each other.
More Lessons In This Unit
- Comparing representations of outcomes for more than two events Study Guide
- Comparing representations of outcomes for two events Study Guide
- Experiments to determine how likely an outcome is Study Guide
- Non-equally likely outcomes Study Guide
- Problem solving with possible outcomes Study Guide
- The scale of likelihoods Study Guide
- Using a Venn diagram to display outcomes for more than two events Study Guide
- Using a Venn diagram to display outcomes for two events Study Guide
- Using an outcome tree to display outcomes for more than two events Study Guide
- Using an outcome tree to display outcomes for two events Study Guide
- Using lists to display outcomes for more than two events Study Guide
- Using lists to display outcomes for two events Study Guide
- Using two-way tables to display outcomes for two events Study Guide
Browse all guides in the Year 9 Maths guide library.