Start by clarifying the helicopter type and whether the balls are loose or packed, then break the problem into estimating the helicopter's interior volume and the volume of a ping pong ball, accounting for packing efficiency. Walk through your assumptions transparently and calculate a final estimate, emphasizing that the process matters more than the exact number.
Pro tip: State your assumptions upfront and invite the interviewer to correct them—this shows collaboration and adaptability, key traits for a PM. Also, mention that the answer should be a range (e.g., 'between X and Y') rather than a single number, reflecting real-world uncertainty.
Ask questions to define the helicopter model (e.g., small vs. large), whether the balls are loose or in boxes, and if the space includes the cockpit and external compartments. This narrows the problem and shows you avoid assumptions.
Approximate the interior space as a cylinder or box using typical dimensions (e.g., 2m wide, 2m high, 5m long) and subtract space taken by seats, equipment, etc. Round numbers for simplicity.
Recall or estimate a ping pong ball's diameter (40mm) and compute its volume as a sphere (4/3πr³). Convert to cubic meters for consistency.
Explain that spheres don't fill space perfectly; random packing achieves ~64% efficiency, while ordered packing can reach ~74%. Use a reasonable factor (e.g., 0.64) to adjust the count.
Divide the effective helicopter volume by the ball volume, apply packing efficiency, and present a range. Sanity-check by comparing to known benchmarks (e.g., a car trunk holds ~10,000 balls).
AI-generated suggestions, not part of the candidate's original notes. May be inaccurate — verify before relying on them.