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A-Level MathematicsYear 2021Q5

10 5 Test A is a simple saliva test designed to detect whether an adult is a user of a particular psychoactive drug. This test is used in a large secure facility where random testing for this drug routinely takes place. Previous research shows that 1% of adults living in the facility are users of this drug. If an adult is a user of this drug, the probability of Test A returning a positive result is 97% If an adult is not a user of this drug, the probability of Test A returning a (false) positive result is 4% (a) Show that the probability that a randomly chosen adult living in this facility, who had a positive Test A result, actually is a user of this drug is 0.1968, correct to 4 decimal places. (6) ___________________________________________ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ ___________________________________________

Paper Source:9ST0_01_que_20211020.pdf

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Exam Specification Info

This question is part of the UK A-Level Mathematics syllabus. In the actual exam, structured questions typically require linking specific keywords to gain full marks. Applaa helps you drill these topics.

Syllabus levelAdvanced Level (A-Level)

SubjectMathematics

Official MarksVariable (2–6 marks)