Question 1

Paper 1, no calculatorHard6 marks

A health service records whether each of 300 participants has a risk factor FF and whether each is diagnosed with a disease DD Figure 1 shows the results.

020406080100120140160180200220240260Number of participants21624519F presentF absentRisk factor statusDiagnosed with DNot diagnosedwith D

A report notes that more participants diagnosed with DD had FF than did not have FF and concludes that diagnosis is more likely among participants with FF

(a)

State the definition of P(A∣B)P(A\mid B) in terms of P(A∩B)P(A\cap B) and P(B)P(B)

[1]
(b)

Use Figure 1 to calculate P(F∣D)P(F\mid D)

[1]
(c)

In light of your answer to (b), test whether FF and DD are independent and assess the report’s conclusion.

[4]

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