Answer:0.806
Step-by-step explanation:
Given
4 % Test false negative i.e. Person is drug user but test is negative
so 96 % are drug user and should with positive test
6 % is false Positive i.e. Person is Non-druggist but test is showing positive
94 % are Non-druggist and test negative
If 19 % of employees use drug
so 100-19=81 % are non drug user
Probability(Employee uses drug if he tests negative)=P
[tex]P=\frac{0.81\times 0.94}{0.81\times 0.94+0.19\times 0.04}[/tex]
[tex]P=\frac{0.761}{0.943}=0.806[/tex]