Suppose that 0.9% of male professional golfers use steroids, and that Max is a male professional golfer who has been randomly selected to take a drug test. The test he has been asked to take has a false positive rate of 1% and a false negative rate of 10%.

0.4490

Step-by-step explanation:

P (tested positive) = P (uses steroid and tested positive) + P (not uses steroid and tested positive)

=0.009*0.9+0.994*0.01=0.01804

Therefore:

Therefore P (uses steroid|tested positive) = P (tested positive & uses steroid) / P (tested positive) = 0.009*0.9/0.01804=0.4490