How Many Tennis Balls Can Fit in an Airplane? A Guide to Answering Estimation Questions in Product Management Interviews
Welcome to the fascinating world of product management interview estimations! This guide aims to equip aspiring and seasoned product managers (PMs) with the tools to tackle estimation questions commonly encountered in FAANG interviews.
Inspired by the popular book ‘Decode and Conquer: Answers to Product Management Interviews,’ we’ll explore how to approach the seemingly unusual yet insightful interview question: “How many tennis balls can fit in an airplane?”
A Structured Approach to Estimation Questions
To methodically answer this question, we’ll employ a framework that breaks down the problem into manageable steps, showcasing both logical thinking and the ability to handle complex problems.
- Understand the Question: Clarify the type of airplane in question. For simplicity, let’s assume a standard Boeing 737.
- Break Down the Problem: We need to estimate the volume of the airplane’s cabin and the volume of a single tennis ball.
- Gather Data: A Boeing 737 has an average cabin volume of approximately 130 cubic meters. A standard tennis ball has a diameter of 6.7 cm, resulting in a volume of roughly 0.16 liters.
- Calculate: Convert the cabin volume from cubic meters to liters (1 cubic meter = 1,000 liters) and divide the airplane’s total volume by the volume of a single tennis ball.
Example Calculation: If the Boeing 737 has a volume of 130,000 liters and a single tennis ball occupies 0.16 liters, then approximately 812,500 tennis balls could fit inside the airplane. Remember, this estimate doesn’t account for seats or irregularities in shape.
Fact Check: Ensure the calculations seem plausible. If the estimated number is significantly higher or lower, recheck the assumptions and calculations.
Effective Communication Tips
- Clearly explain your thought process to the interviewer and don’t hesitate to ask clarifying questions.
- Use simple language to explain your calculations and assumptions.
- Be prepared to justify your approximations and consider alternative scenarios if prompted.
Conclusion
Estimation questions are less about the exact answer and more about the thought process and problem-solving skills. Structured frameworks are invaluable tools in your interview arsenal. Practice using them to become proficient in deconstructing complex problems and delivering confident, clear responses. Remember to stay calm, structured, and communicate effectively throughout your response.