Year 9 - Maths
The scale of likelihoods
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 show the likelihood of an outcome on a scale.
Key Notes
- A scale can be drawn showing the 5 different likelihoods.
- The likelihood scale can be evaluated to understand why only 5 states are shown.
- Different outcomes for an event can be placed on the likelihood scale.
Vocabulary To Learn
- Impossible: An outcome is impossible if there is no possibility that it can happen.
- Certain: An outcome is certain if it is guaranteed to happen.
- Even chance: An outcome has even chance if its likelihood of happening is the same as its likelihood of not happening.
Common Mistakes To Avoid
- 'Equal chance' means the same as 'even chance'.
3 Quick Questions (With Answers)
1. Solve this in steps: explain the method from this lesson and why each step matters.
A scale can be drawn showing the 5 different likelihoods. The likelihood scale can be evaluated to understand why only 5 states are shown.
2. Use this key word in a maths sentence and explain it clearly. 'Impossible'
An outcome is impossible if there is no possibility that it can happen. Use this word when showing your method, then check your final answer is reasonable.
3. Spot and fix this common maths mistake.
Mistake: 'Equal chance' means the same as 'even chance'. Correction: When a trial has more than two possible outcomes which are all equally likely to happen, each outcome has less than an even chance of happening. E.g. each number on a dice has the same likelihood of being rolled, but each is less than an even chance.
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
- Equally likely outcomes 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
- 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.