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GCSE Probability
Probability Trees
Learn probability trees as part of understand chance, calculate probabilities and use probability trees for multi-stage events.
Key idea
Define the possible outcomes clearly, then compare favourable outcomes with the total outcomes.
What you will learn
Use probability trees meaning confidently.
Use probability trees representations confidently.
Use probability trees methods confidently.
Use probability trees applications confidently.
Success checklist
✓I can explain what probability trees means.
✓I can choose a suitable method without being told.
✓I can show clear working and check my answer.
Worked example
A fair dice is rolled. Find P(rolling a 6).
Step 1
There are 6 equally likely outcomes.
Step 2
Only one outcome is a 6.
Step 3
P(6) = 16.
Answer
16
Quick practice
Question 1
Find P(heads) for a fair coin.
Question 2
A bag has 3 red and 5 blue counters. Find P(red).
Question 3
List the outcomes for tossing two coins.
Related resources
These are linked to the wider Probability topic for now.