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Estimationstretch
Estimate how many people are on flights over the US right now.
How to approach it
Start with flights in the air at a given moment, then multiply by average passengers per flight.
How a strong answer opens
“I'll estimate how many flights are in the air at one moment, from daily flights and average flight length, then multiply by passengers per flight.”
Outline of a strong answer
Try answering out loud for a few minutes before you open this.
- Clarify: commercial passenger flights, a typical weekday afternoon
- Estimate daily US flights
- Average flight length in hours and hours of active flying per day
- Flights in the air at once = daily flights x hours each / active hours
- Average passengers per flight
- Multiply, then sanity-check against a big airport's daily passenger count
Where this question usually goes wrong
Multiplying daily flights by passengers and calling that the number in the air right now, forgetting most flights are on the ground at any given moment.
Learn the method
Top-down and bottom-up in Module 3, Estimation.
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