Learn by Doing – Conditional Probability and the General Multiplication Rule
An overheating engine can quickly cause serious damage to a car, and therefore a dashboard red warning light is supposed to come on if that happens.
In a certain model car, there is a 3% chance that the engine will overheat (event H).
The probability of the warning light showing up (event W) when it should (i.e., when the engine is really overheating) is 0.98. However, 1% of the time the warning light appears for no apparent reason (i.e., when the engine temperature is normal).
This document is linked from Conditional Probability and Independence.