A jar contains 12 marbles. 6 of the marbles are yellow, 4 of the marbles are green, and 2 of the marbles are purple. Sarah takes two marbles at random from the jar.
Work out the probability that both of the marbles Sarah takes are the same colour.
You must show your working.
Practise Edexcel GCSE Maths Conditional Probability with exam-style questions for Foundation and Higher tier. 28 questions, matched to the Edexcel GCSE Maths (1MA1) specification and written in Paper 1, Paper 2 and Paper 3 style. Every question includes a full worked solution and mark scheme, so you can see where marks are awarded rather than just whether you got the answer right.