Deriving the Number of Hexagon Panels on a Classic Soccer Ball
Quick Overview
An analytical-thinking question from a PM interview that asks how many hexagon panels a classic soccer ball has and how you would work it out. It tests clarifying an ambiguous object, choosing between a structural argument and a surface-area estimate, getting the arithmetic right and sanity-checking the result.
Deriving the Number of Hexagon Panels on a Classic Soccer Ball
Company: Amazon
Role: Product Manager
Category: Product / Decision Making
Difficulty: medium
Interview Round: Other
How many hexagons does a football have? Commit to a number and walk the interviewer through the reasoning that gets you there; the way you reach the answer matters as much as the answer.
```hint Look at one corner
Instead of measuring panels, consider how they fit together: which shapes meet at each corner of the ball, and how many panels share each seam. Facts like these can be turned into equations.
```
### Clarifying Questions
- Which ball is meant: the classic soccer ball with black pentagons and white hexagons, an American football, or a modern match ball whose panels have other shapes?
- Can I look at a ball or a picture of one, or should I reason it out from memory?
- Is an exact count expected, or is a well-reasoned estimate with a sanity check enough?
### What a Strong Answer Covers
- Settling which ball is meant and stating the assumptions about its panels before counting anything.
- A structured method: either a geometric argument that yields an exact count or a surface-area estimate with every input labeled as an assumption.
- Correct arithmetic and a check that the final numbers are consistent with each other and with the ball's pattern.
- Judgment about which method is more reliable and how sensitive an estimate is to its inputs.
### Follow-up Questions
- How many pentagons does the same ball have, and how many seams must be stitched to assemble it?
- If you knew only the ball's diameter and a rough panel width, how would you estimate the count, and how far off could you be?
- A manufacturer wants a ball made of fewer, larger panels. What changes for players, and what trade-offs come with it?
Overview: An analytical-thinking question from a PM interview that asks how many hexagon panels a classic soccer ball has and how you would work it out. It tests clarifying an ambiguous object, choosing between a structural argument and a surface-area estimate, getting the arithmetic right and sanity-checking the result.
Deriving the Number of Hexagon Panels on a Classic Soccer Ball
Amazon
May 31, 2024
mediumProduct ManagerOtherProduct / Decision Making
0
0
How many hexagons does a football have? Commit to a number and walk the interviewer through the reasoning that gets you there; the way you reach the answer matters as much as the answer.
Clarifying Questions Guidance
Which ball is meant: the classic soccer ball with black pentagons and white hexagons, an American football, or a modern match ball whose panels have other shapes?
Can I look at a ball or a picture of one, or should I reason it out from memory?
Is an exact count expected, or is a well-reasoned estimate with a sanity check enough?
What a Strong Answer Covers Guidance
Settling which ball is meant and stating the assumptions about its panels before counting anything.
A structured method: either a geometric argument that yields an exact count or a surface-area estimate with every input labeled as an assumption.
Correct arithmetic and a check that the final numbers are consistent with each other and with the ball's pattern.
Judgment about which method is more reliable and how sensitive an estimate is to its inputs.
Follow-up Questions Guidance
How many pentagons does the same ball have, and how many seams must be stitched to assemble it?
If you knew only the ball's diameter and a rough panel width, how would you estimate the count, and how far off could you be?
A manufacturer wants a ball made of fewer, larger panels. What changes for players, and what trade-offs come with it?