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Year 11 - Maths

Algebra in tree and Venn diagrams

Conditional probability

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 apply your knowledge of probability equations to tree and Venn diagrams to solve problems.

Key Notes

  • An equation can be constructed to find unknown probabilities in tree diagrams
  • This equation can be manipulated and solved to find unknown probabilities in tree diagrams
  • An equation can be constructed to find unknown probabilities in Venn diagrams
  • This equation can be manipulated and solved to find unknown probabilities in Venn diagrams

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.
  • Probability tree: Each branch of a probability tree shows a possible outcome from an event or from a stage of a trial, along with the probability of that outcome happening.
  • Independent events: Event A is independent of event B if the probability of event A occurring is not affected by whether or not event B occurs.
  • Mutually exclusive: Mutually exclusive events have no outcomes in common.
  • Venn diagram: Venn diagrams are a representation used to model statistical/probability questions. Commonly circles are used to represent events.

Common Mistakes To Avoid

  • When variables are used in diagrams, pupils may be unsure whether it represents a probability, frequency or a particular outcomes.

3 Quick Questions (With Answers)

1. Solve this in steps: explain the method from this lesson and why each step matters.

An equation can be constructed to find unknown probabilities in tree diagrams. This equation can be manipulated and solved to find unknown probabilities in tree diagrams.

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 variables are used in diagrams, pupils may be unsure whether it represents a probability, frequency or a particular outcomes. Correction: Variables can be used to represent either of these pieces of information. It can be helpful to start a problem by writing down what the variables represent (e.g. "Let x = the total number of marbles).

More Lessons In This Unit

Browse all guides in the Year 11 Maths guide library.