Conditional Probability

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A researcher surveys 100 teenagers about their social media usage. The apps tracked are Snapchat ( $S$ ), Instagram ( $I$ ), and TikTok ( $T$ ).

10 teenagers use all three apps
20 teenagers use both Snapchat and Instagram
18 teenagers use both Instagram and TikTok
25 teenagers use both Snapchat and TikTok
50 teenagers use Snapchat
45 teenagers use Instagram
55 teenagers use TikTok

Draw a Venn diagram to represent this information.

[3]

One of the teenagers is selected at random. Given they use TikTok, find the probability they do not use Instagram.

[3]

Conditional Probability Questions

Practise Edexcel A Level Maths Conditional Probability with exam-style questions for A Level Maths. 100 questions covering Set Notation, Conditional Probability, Conditional Probabilities in Venn Diagrams, Probability Formulae, and Tree Diagrams, matched to the Edexcel A Level Maths (9MA0) 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.