Part 2: Worked-out Example 1: Breathalyzers



scenario:

Imagine you work in a police department. Your department often uses Breathalyzers to test whether drivers are driving under the influence of alcohol. Based on the previous 100 cases in which a person's sobriety was later verified by a blood test, you know the following. Among the 100 cases,
15 drivers were sober but tested positive;
8 drivers were drunk and tested positive;
75 drivers were sober and tested negative;
2 drivers were drunk but tested negative.