Question

Suppose you have data that shows that 12% of athletes test positive for steroids. You also know that 11% of athletes test positive for steroids and actually use steroids. What is the probability that an athlete uses steroids, given that he tests positive?

Answer 1

0.37



0.43



0.51



0.67



0.92

Answer 2

This is called conditional probability. Say
A : probability of an athlete using steroids.
B : probability that an athlete tests positive.
\[P(A|B) = \frac{ P(A \cap B) }{ P(B) }\] \(P(A \cap B) = 0.11\)