Results from a marijuana drug test study showed 143 subjects with positive test results including 24 false positive results. There were 157 negative results, including 3 false negative results. What is the probability that a randomly selected subject did not use marijuana?

Question

Quizplus · Accepted Answer

The total number of subjects is 143 + 157 = 300. The number of subjects who did not use marijuana includes those with true negative results and false positive results, which is 157 - 3 (true negatives) + 24 (false positives) = 178. Therefore, the probability that a randomly selected subject did not use marijuana is 178 / 300 = 0.593.

Results from a Marijuana Drug Test Study Showed 143 Subjects