# Tree Diagrams

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## Tree Diagrams

If you can master Tree Diagrams you've got probability sorted!

**Here's a diagram to help you understand them:**

**Here's an example:**

A bag contains 6 red marbles and 4 blue marbles. A marble is drawn at random and not replaced. A second marble is then drawn.

**Below is a tree diagram to show the probabilities:**

The probabilities at the ends of the branches are found by multiplying the probabilities going across.

So to work out the probability of getting one marble of each colour, just **add** the ones we want going down:

The diagram below shows a tree diagram for the same question but this time there are 5 red balls and 3 green balls.

**Click on the question marks to reveal the probabilities:**