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2.3.10 Conditional probabilities (A-level only)

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Question 39

A researcher surveys 100 teenagers about their social media usage. The apps tracked are Snapchat (SSS), Instagram (III), and TikTok (TTT).

  • 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
a.

Draw a Venn diagram to represent this information.

[3]
b.

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

[3]
Markscheme

2.3.10 Conditional probabilities (A-level only) Questions

  1. A Level
  2. /Maths
  3. /2.3.10 Conditional probabilities (A-level only)

164 exam-style questions on OCR (MEI) A Level Maths 2.3.10 Conditional probabilities (A-level only). Each one has a worked solution and a mark scheme showing where the marks go.

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