This pertains to the following post:
When to use Total Probability Rule and Bayes' Theorem.
I understand the ideas and can implement them if I'm told what B and the partitions A are in the question - or that i'm meant to use the law of total prob - but always get stuck in these type of questions if I don't know specifically what method I'm meant to use. I get the venn diagrams below but can never work out from the questions what should be B and what the partitions A_1, A_2, etc represent.
Any tips would be great.