A tech support center receives inquiries through three channels: Phone, Email, and Live Chat. 45% of inquiries come through Phone, 40% through Email, and 15% through Live Chat.
The probability that an inquiry remains unresolved after the first contact is:
Draw a tree diagram to illustrate this situation.
An inquiry is selected at random. Find the probability it is unresolved.
Given that an inquiry is unresolved, find the probability it was made via the Phone channel.
111 exam-style questions on WJEC A Level Maths 4.1.1 Probability (A-level only). Each one has a worked solution and a mark scheme showing where the marks go.