Year 11 - Maths
Frequency trees
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 draw and use a frequency tree to calculate probabilities.
Key Notes
- There are key differences between frequency trees and probability trees
- Frequency trees are constructed using frequencies
- Frequency trees display information on how often an outcome happened within a set number of trials
Vocabulary To Learn
- Frequency: The frequency is the number of times an event occurs; or the number of individuals (people, animals etc.) with some specific property.
- Tree diagram: Tree diagrams are a representation used to model statistical/probability questions. Branches represent different possible events or outcomes.
- Probability: The probability that an event will occur is the proportion of times the event is expected to happen in a suitably large experiment.
Common Mistakes To Avoid
- Pupils may be tempted to always use the total frequency from a tree as the denominator of any fraction.
3 Quick Questions (With Answers)
1. Solve this in steps: explain the method from this lesson and why each step matters.
There are key differences between frequency trees and probability trees. Frequency trees are constructed using frequencies.
2. Use this key word in a maths sentence and explain it clearly. 'Frequency'
The frequency is the number of times an event occurs; or the number of individuals (people, animals etc.) with some specific property. Use this word when showing your method, then check your final answer is reasonable.
3. Spot and fix this common maths mistake.
Mistake: Pupils may be tempted to always use the total frequency from a tree as the denominator of any fraction. Correction: The denominator of the fraction should be the total frequency of the group that is being selected from. This could be the total population or it could be a subgroup of the population.
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
- Combinations 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
- 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.