probability question

Question

Refer to the sample data for​ pre-employment drug screening shown below. If one of the subjects is randomly​ selected, what is the probability that the test result is a false​ positive? Who would suffer from a false positive​ result? Why?

Positive Test Result Negative Test Result

Subject Uses Drugs 42 11

Subject Is Not a Drug User 20 27

Answer 1

A false positive would be a positive test result from a subject who is not a drug user. That would be 20 people out of 100, for a probability of 0.2. People who are false positives will end up not being employed because of the false result.