A bag contains 9 blue balls and 3 red balls. A ball is selected at random from the bag and its colour is recorded. The ball is not replaced. A second ball is selected at random and its colour is recorded.
Draw a tree diagram to represent the information.
Find the probability that the second ball selected is red.
Find the probability that both balls selected are red, given that the second ball selected is red.
11 exam-style questions on Edexcel A Level Old Maths Probability. Each one has a worked solution and a mark scheme showing where the marks go.