How many users saw at least one violative Pin?
Measurement & estimationHardProblem. Prevalence is low and stable. In a leadership review, an executive asks a different question: "how many of our users actually saw something bad last month?" Nobody has that number. How would you produce it?
Before you reveal: say your answer out loud, as if you were in the real interview — get your reasoning across clearly first. There is no single correct answer: reading what the interviewer is really after and defending your own thinking is what makes an answer strong.