Estimation question

Estimate the number of planes that are in the air in an hour.

Practice this question out loud. An AI interviewer asks it, follows up like a real interviewer would, and scores your answer. Type or speak.

What this question tests

Structured Fermi estimation using known aviation facts and clear assumption chains.

Clarify scope: estimate globally, at a typical hour, not just US airspace, unless the interviewer specifies otherwise.
Estimate total commercial flights per day worldwide, using an assumed figure like 100,000 flights a day as a starting point.
Estimate average flight duration, assumed around 2 hours, to convert daily flights into simultaneous flights in the air.
Compute: total daily flights times average duration in hours, divided by 24, gives an estimate of planes airborne at any given hour.
Sanity check against known facts, like flight tracking sites showing roughly 9,000 to 20,000 planes in the air at peak times.
State the result as a range with the key assumption (100,000 daily flights, 2-hour average) called out explicitly.

Uses the flights-times-duration-divided-by-24 method, a standard and defensible Fermi technique for this class of problem.
States the 100,000 daily flights assumption explicitly rather than presenting it as fact.
Cross-checks the result against a real-world reference point, like known flight-tracker figures, to validate plausibility.
Delivers a range, not a single overly precise number.

Guessing a final number without showing the flights-times-duration calculation.
Ignoring that 'an hour' likely means airborne planes at any given moment, not total flights per hour.

Chapters of the AI PM course that teach what this question tests.