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Google·Product Manager·Onsite - Product Sense / Strategy·Intermediate

Intermediate
Jun 2026

Summary

Google PM interview with a classic estimation question. Pretty standard case format but the open-ended airport framing tripped me up more than I expected.

Questions Asked (1)

Q1

Pick an airport and estimate the number of people going through the security scan in a single day.

Product Analytics & MetricsAdaptability & Ambiguity
Author's notes

I picked a mid-size airport thinking it'd be easier to reason about than a hub like JFK, but then I second-guessed myself halfway through because I had no anchor for gate counts.

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AI HintsAI Generated

Suggested Approach

Choose a well-known airport (e.g., SFO) and break the problem into flights and passengers per flight, then apply a load factor and the proportion of passengers who go through security (departing + some connecting). Use round numbers and state assumptions clearly, then sanity-check the final estimate against known airport throughput.

Pro tip: Mention that you would validate the estimate with real-world data (e.g., TSA throughput reports) and adjust for seasonality or time of day, showing you balance top-down logic with empirical checks.

1. Clarify scope and choose airport

Confirm whether the estimate is for departing passengers only or includes connecting passengers, and pick a specific airport (e.g., SFO) to anchor the analysis.

2. Estimate daily flights

Calculate the number of departing flights per day by considering runway capacity, operating hours, and typical airline schedules (e.g., 1,000 flights/day).

3. Estimate passengers per flight

Use average aircraft capacity (e.g., 150 seats) and a realistic load factor (e.g., 80%) to get ~120 passengers per flight.

4. Determine security scan volume

Multiply flights by passengers per flight to get total departing passengers, then add connecting passengers who also clear security (if applicable) and subtract any exemptions (e.g., crew, infants).

5. Sanity-check and refine

Compare the result to known benchmarks (e.g., TSA screens ~2 million people/day nationally) and adjust for airport size, time of day, or seasonality.

Key Points to Mention

  • Clearly state all assumptions (airport choice, load factor, aircraft size, connecting passenger percentage).
  • Use a top-down approach: flights × passengers per flight.
  • Differentiate between originating and connecting passengers, as both may go through security.
  • Consider peak vs. off-peak hours and how that affects daily totals.
  • Sanity-check the final number against real-world data or known airport statistics.
  • Acknowledge potential sources of error and how you would validate the estimate.

AI-generated suggestions, not part of the candidate's original notes. May be inaccurate — verify before relying on them.