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4.1.1 Probability (A-level only)

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Question 11

A city has three health clinics: Alpha, Beta, and Gamma. 45% of diagnostic tests are performed at Alpha, 30% at Beta, and 25% at Gamma.

At clinic Alpha, the probability of a false positive result is 2%. At clinic Beta, the probability of a false positive result is 3%. At clinic Gamma, the probability of a false positive result is 4%.

a.

Draw a tree diagram to show this information.

[3]
b.

A test result is selected at random. Find the probability it is a false positive.

[2]
c.

Given that the test result is a false positive, find the probability it was performed at clinic Alpha.

[3]
Markscheme

4.1.1 Probability (A-level only) Questions

  1. A Level
  2. /Maths
  3. /4.1.1 Probability (A-level only)

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.

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