Estimation question
How would you identify all the potholes in the United States?
- Estimation
- Medium
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What this question tests
Estimation combined with practical systems thinking about data collection at scale.
How to approach it
- Clarify the question is really two parts: estimating the total number of potholes, and designing a method to identify them.
- Estimate total US road miles using a general known figure, then assume an average pothole density per mile based on road condition surveys.
- Multiply road miles by assumed potholes per mile to get a rough total count, stating both inputs as explicit assumptions.
- Propose an identification method: using dashcam or phone accelerometer data from ride-hailing or mapping app users to detect vibration signatures consistent with potholes.
- Address validation: crowdsourced reports (like Waze) combined with computer vision on existing street-view imagery to confirm and geolocate them.
- Note the trade-off between coverage speed (crowdsourced) and accuracy (dedicated sensor sweeps).
What a strong answer includes
- Splits the answer clearly into the estimation part and the practical detection-system part, addressing the full question.
- States both the road-mileage and pothole-density assumptions explicitly, e.g. 4 million miles of road, 2 potholes per mile, marked as assumptions.
- Proposes a concrete, existing-technology detection method, accelerometer data from connected vehicles, rather than an abstract idea.
- Flags the trade-off between crowdsourced speed and dedicated-sensor accuracy as a real design decision.
Common mistakes
- Answering only the estimation half and ignoring the 'how would you identify them' half of the question.
- Proposing manual road inspection at national scale without considering cost or feasibility.
Likely follow-up questions
- How would you validate crowdsourced pothole reports?
- How would you prioritize which potholes get fixed first?
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Learn the skill behind it
Chapters of the AI PM course that teach what this question tests.
- Chapter 2: Data fluency: SQL, logs, and reading the truth yourself
- Chapter 9: Prove it paid off: outcomes, economics, and pricing
- Chapter 14: Get the job: the AI PM interview loop