Probability tree diagrams make answering probability questions much easier.  Make sure you can draw tree diagrams.

Key facts

  • Multiply the numbers along the branches to get end results
  • The numbers on any set of branches that meet at a point must always add up to 1
  • Check your diagram is correct by checking that the end results add up to 1
  • To answer a question, add up the relevant end results

Probability revision questions