Help with false positives

Question

A drug testing company advertises a test for steroids that is 93.5% effective at detecting steroid use. It has a true negative effectiveness of 93.5%. Suppose 8% of 10,000 professional cyclists are believed to be using steroids.

Suppose the haplessly named Lance Robustcalve tests positive for steroid use. What is the probability that he's really not using steroids? (Round your probability to the nearest tenth of a percent!)

Answer 1

6.5:93.5................