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2.3 Probability

2.3 Probability

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Question 47

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 Probability Questions

  1. A Level
  2. /Maths
  3. /2.3 Probability

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.

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