How to use a probability tree

Visit www.mathswrap,co.uk for real maths, tips and tricks.
Probability tree diagrams are just a picture that show all the possible outcomes from a series of events. They can be quite useful as probability needs some careful thought.
This video deals with a GCSE question: There are 3 strawberry yoghurts and 4 peach yoghurts in a fridge. Kate takes a yoghurt at random from the fridge. She eats the yoghurt. She then takes a second yoghurt at random from the fridge. Work out the probability that both yoghurts are the same flavour.