3QUESTION 3 OF 3
Answer & explanation
The official answer, with Fermi’s reasoning step by step.
Answer & explanation
Official answer
14
Filet-O-Fish
How to estimate it
Fermi’s official “Napkin math”
You eat about 2,000 calories a day, around 5 Filet-O-Fish. A great white weighs maybe 10 times what you do. But how hard does a fish burn fuel? Far less than us for its size, maybe a fifth.
- You, per day
- ~5 Filet-O-Fish
- Shark is ~10x heavier
- × 10
- Fish burn ~1/5 as much
- ÷ 5
- 5 × 10 ÷ 5
- ≈ 10
Rounded assumptions may give a slightly different estimate. The official answer above is the game’s reference value.
Source calculation & reference
- White shark daily energy use (Semmens et al. 2013, median)
- ≈ 22.1 MJ ≈ 5,300 kcal
- One Filet-O-Fish (McDonald's US)
- ÷ 380 kcal
- 5,300 ÷ 380
- ≈ 14
Reference cited by Fermi: Semmens et al. 2013, Scientific Reports (white shark field energy use); McDonald's US nutrition facts (Filet-O-Fish, 380 Cal)
How close was your guess?
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Compare by ratio: divide the larger number by the smaller one. The closer to 1×, the better.