A drawer contains 8 white socks, 6 black socks, and 6 grey socks. Two socks are pulled from the drawer at random without replacement.
Draw a tree diagram to represent this information.
Find the probability that the two socks pulled are both grey.
Given that at least one of the socks pulled is black, find the probability that both socks are black.
200 exam-style questions on OCR A Level Maths 2.3 Probability, covering 2.3.1 Mutually exclusive and independent events, 2.3.2 Diagrams to assist probability calculations, 2.3.3 Conditional probability (A-level only), 2.3.4 Conditional probability from first principles (A-level only), and 2.3.5 Modelling with probability. Each one has a worked solution and a mark scheme showing where the marks go.