SAT Math Multiple Choice Question 772: Answer and Explanation

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Question: 772

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A researcher is studying the effectiveness of a method for testing the presence of an antibody in a patient's bloodstream. The table above shows the results of 1,000 patient trials. According to these data, what is the probability that a patient who has the antibody will nevertheless have a negative test result?

  • A. 0.01
  • B. 0.04
  • C. 0.05
  • D. 0.20

Correct Answer: B



Problem Solving and Data Analysis (quadratics) MEDIUM

The table indicates that a total 500 patients had the antibody and that 20 of these patients nevertheless had a negative test result. Therefore the probability of this result is 20/500 = 0.04.

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