Year 9 - Maths
Calculating theoretical probabilities from a table (one event)
Probability: theoretical probabilities
Study Hub
Study Guides
This pupil-friendly study guide includes a unit summary, clear notes, common mistakes, and quick questions with answers.
Unit Summary
In this unit we build upon the concept of likelihood to work more mathematically with more measurable probability using fraction and decimal representations to both interpret and calculate. We revisit and develop ways to represent and compare probabilities.
Lesson Summary
You will learn to find theoretical probabilities from a table showing the possible outcomes for one event.
Key Notes
- The probability of an outcome can be found by considering a table showing all possible outcomes.
- The probability of a set of outcomes can be found by considering a table showing all possible outcomes.
- A table of all possible outcomes can help us find a probability, even when the outcomes are not equally likely.
Vocabulary To Learn
- Probability: The probability that an event will occur is the proportion of times the event is expected to happen in a suitably large experiment.
- Theoretical probability: A theoretical probability is a probability based on counting the number of desired outcomes from a sample space where all individual outcomes are equally likely.
- Frequency: The frequency is the number of times an event occurs; or the number of individuals (people, animals, etc) with some specific property.
Common Mistakes To Avoid
- When finding the probability of an outcome based on a frequency table, pupils may use the number of different categories as the denominator rather than the total frequency.
3 Quick Questions (With Answers)
1. Solve this in steps: explain the method from this lesson and why each step matters.
The probability of an outcome can be found by considering a table showing all possible outcomes. The probability of a set of outcomes can be found by considering a table showing all possible outcomes.
2. Use this key word in a maths sentence and explain it clearly. 'Probability'
The probability that an event will occur is the proportion of times the event is expected to happen in a suitably large experiment. Use this word when showing your method, then check your final answer is reasonable.
3. Spot and fix this common maths mistake.
Mistake: When finding the probability of an outcome based on a frequency table, pupils may use the number of different categories as the denominator rather than the total frequency. Correction: When strawberry flavoured sweets have a frequency of 11, it means that 11 of the sweets in the box are strawberry flavoured. The box of sweets could be visually represented with each sweet being shown by the first letter of its flavour.
More Lessons In This Unit
- Calculating theoretical probabilities from lists (one event) Study Guide
- Calculating theoretical probabilities from probability tree diagrams (one event) Study Guide
- Calculating theoretical probabilities from probability trees (two events) Study Guide
- Calculating theoretical probabilities from two-way tables (two events) Study Guide
- Calculating theoretical probabilities from Venn diagrams (one event) Study Guide
- Calculating theoretical probabilities from Venn diagrams (two events) Study Guide
- Checking listing possible outcomes Study Guide
- Comparing multiple representations to calculate theoretical probabilities Study Guide
- Comparing multiple representations to calculate theoretical probabilities for combined events Study Guide
- Problem solving with theoretical probability Study Guide
- Summing probabilities Study Guide
- The probability scale Study Guide
Browse all guides in the Year 9 Maths guide library.