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Estimationstandard
How many tennis balls are sold in the US each year?
How to approach it
Segment buyers. Regular players, casual players, clubs and dog owners all buy tennis balls at very different rates.
How a strong answer opens
“I'll segment buyers, because regular players, casual players, clubs and dog owners buy tennis balls at very different rates. Just to confirm, you mean units sold, including to non-players?”
Outline of a strong answer
Try answering out loud for a few minutes before you open this.
- Clarify: units sold, all buyers including non-players
- Estimate share of Americans who play tennis at least sometimes
- Split into frequent and casual players with balls per year each
- Add clubs, schools and tournaments
- Add non-tennis uses, such as dog toys
- Sum the segments and sanity-check the total
Where this question usually goes wrong
Applying one buying rate to every American instead of segmenting by how often each group actually buys.
Learn the method
Top-down and bottom-up in Module 3, Estimation.
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