Basic Tree Diagram Structure

Part of Tree Diagrams · Section 3 of 7

DiagramUnit: ProbabilityGCSE

Example: Two Coin Flips

First Coin       Second Coin      Outcome    Probability
                      H ————————— HH        1/2 × 1/2 = 1/4
    H (1/2) ————————/
   / \               \
  /   \               T ————————— HT        1/2 × 1/2 = 1/4
Start  \
  \     \
   \     \
    T (1/2) ————————/
                     \
                      H ————————— TH        1/2 × 1/2 = 1/4
                      
                      T ————————— TT        1/2 × 1/2 = 1/4

Check: All probabilities add to 1: 1/4 + 1/4 + 1/4 + 1/4 = 1 ✓

This diagram covers Basic Tree Diagram Structure within Tree Diagrams for GCSE Mathematics. Revise Tree Diagrams in Probability for GCSE Mathematics with 15 exam-style questions and 20 flashcards. This is a high-frequency topic, so it is worth revising until the explanation feels precise and repeatable. It is section 3 of 7 in this topic. Focus on the labels, the relationships between parts, and the explanation that turns the diagram into an exam-ready answer.

Practice questions for Tree Diagrams

A fair coin is flipped twice. In a tree diagram, what must the probabilities on the branches from the same point always add up to?

  • A. 0
  • B. 1
  • C. The number of branches
  • D. The total number of outcomes
1 markfoundation

Explain the two key rules used when calculating probabilities from a tree diagram. Your answer should refer to both the multiplication rule and the addition rule.

3 marksstandard

Quick recall flashcards

What is a tree diagram?
A visual representation of all possible outcomes in multi-stage events
What does each branch in a tree diagram represent?
A possible outcome at that stage of the experiment

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