A drug-testing laboratory produces false negative results 2% of the time and false positive results 5% of the time. Suppose that the laboratory has been hired by a company in which 10% of the employees use drugs.
a) If an employee tests positive for drug use, what is the probability that they actually use drugs?
b) What is the probability that a nondrug user will test positive for drug use twice in a row?
c) What is the probability that someone who tests positive twice in a row is not a drug user?