1QUESTION 1 OF 3
Answer & explanation
The official answer, with Fermi’s reasoning step by step.
Answer & explanation
Official answer
60,000
liters
How to estimate it
Fermi’s official “Napkin math”
Start with average human life expectancy, call it about 75 years. Doctors say drink roughly 2 liters of water a day.
- Average human life expectancy
- ≈ 75 years
- Daily water intake
- ≈ 2 liters
- 2 × 365 × 75
- ≈ 54,750
Start with average human life expectancy, call it about 75 years. Doctors say drink roughly half a gallon of water a day.
- Average human life expectancy
- ≈ 75 years
- Daily water intake
- ≈ 0.5 gallons
- 0.5 × 365 × 75
- ≈ 13,700
Rounded assumptions may give a slightly different estimate. The official answer above is the game’s reference value.
Source calculation & reference
- Average human life expectancy (WHO)
- ≈ 73.8 years
- EFSA adequate intake for total water, including food (2.0 L women, 2.5 L men)
- × 2.25 L per day
- 73.8 × 365 × 2.25 L
- ≈ 60,000 L
Reference cited by Fermi: WHO global life expectancy · EFSA adequate intake for total water (2010)
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