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Estimationwarm-up
How many diapers are used in the US in a year?
How to approach it
Count children in diapers, then multiply by changes per day and days per year.
How a strong answer opens
“I'll count children in diapers at any moment, from about 3.5 million births a year and roughly two and a half years in diapers, then multiply by changes per day.”
Outline of a strong answer
Try answering out loud for a few minutes before you open this.
- Births per year, about 3.5 million
- Years in diapers, about 2.5
- Children in diapers at any time
- Diapers per day, with more for newborns
- Multiply by 365
- Add adult products if in scope
Where this question usually goes wrong
Forgetting that children stay in diapers for more than two years, or using newborn change rates for toddlers.
Learn the method
The approach in five steps in Module 3, Estimation.
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