Estimate the Drone Fleet a Service Covering the San Francisco Bay Area Would Need
Company: Google
Role: Product Manager
Category: Product / Decision Making
Difficulty: medium
Interview Round: Other
Estimate how many drones it would take to run a drone service across the San Francisco Bay Area. The prompt does not say what the drones are for or what it means to "serve" the region, so settle the scope first. Then build the estimate step by step, state each assumption with round numbers, and finish with a sanity check of your result.
```hint Size for the busiest hour
A fleet has to keep up when demand is highest, not with the daily average. Work out how many jobs one drone can finish in an hour, counting everything that happens between flights.
```
### Clarifying Questions
- What will the drones do: deliver meals, groceries or parcels, carry medical supplies, or something else such as aerial inspection? The use case sets the payload, the trip length and the demand.
- Which area counts as the Bay Area: the nine counties around the bay, or only the dense urban core?
- What does "serve" mean here: meeting all demand within a target delivery time at the peak, or just offering coverage everywhere at a lower service level?
- Should the estimate describe a mature service with steady adoption, or the fleet needed at launch?
### What a Strong Answer Covers
- A clearly scoped use case and a defined service level that the fleet must meet.
- A demand model built from population or households, the share that drones can reach, adoption and order frequency, converted to peak-hour demand.
- Per-drone capacity from a full cycle: flight distance and speed, time at the drop-off, loading, and battery charging or swapping.
- Adjustments for maintenance, weather, spares and uneven demand across the region, with every assumption labeled.
- A sanity check of the final number and the assumptions it is most sensitive to.
### Follow-up Questions
- How does your answer change if drones must recharge on the pad after every flight instead of swapping batteries?
- How many launch hubs would this fleet need, and where would you put the first ones?
- Which single assumption moves your answer most, and how would you get real data for it before committing to a fleet purchase?
Overview: A product manager estimation question asking how many drones a company would need to run a drone service across the San Francisco Bay Area. It tests scoping an open use case, building demand from population and adoption, converting it to peak-hour drone capacity, and sanity-checking the final fleet size.