A Random Person Is Selected from a Large Population in Which

question 47

Multiple Choice

A random person is selected from a large population in which 5% are users of a dangerous illegal drug.A drug test that correctly identifies users 99% of the times and nonusers 95% of the time (this percentage is called "specificity" of the test) is administered to this individual and gives a positive result.What specificity would actually be required to conclude that the probability that this individual is actually a user of this drug is 0.75?

• A) 0.965
• B) 0.973
• C) 0.978
• D) 0.983
• E) 0.985