A large company gives a new employee a drug test. The False-Positive rate is 3% and the False-Negative rate is 2%. In addition, 2% of the population use the drug. The employee tests positive for the drug. What is the probability the employee uses the drug?

What I try:

X={employee uses drugs}

Y={employee tests positive in the drug test}

P(X|Y) = 0.97

P(notX|Y) = 0.03

P(X|notY) = 0.02

P(notX|notY) = 0.98

P(X) = 0.02

What I try:

X={employee uses drugs}

Y={employee tests positive in the drug test}

P(X|Y) = 0.97

P(notX|Y) = 0.03

P(X|notY) = 0.02

P(notX|notY) = 0.98

P(X) = 0.02