SOLUTION: Some drug tests are about 90% reliable. This means that there is a probability of 0.9 that the test will correctly identify a drug user or a nonuser. To be safe, each person is tes

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Question 1042799: Some drug tests are about 90% reliable. This means that there is a probability of 0.9 that the test will correctly identify a drug user or a nonuser. To be safe, each person is tested twice. What is the probability that a drug user will fail at least one of the tests? (Round your answer to four decimal places.)
Answer by stanbon(75887) About Me  (Show Source):
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Some drug tests are about 90% reliable. This means that there is a probability of 0.9 that the test will correctly identify a drug user or a nonuser. To be safe, each person is tested twice. What is the probability that a drug user will fail at least one of the tests? (Round your answer to four decimal places.)
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P(fail >= 1 test) = 1 - P(pass both) = 1-0.9^2 = 1-0.81 = 0.19
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Cheers,
Stan H.
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