Ecology & populations · SL/HL
Population growth
Find absolute, percentage and average population changes.
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Number formats & units
Use decimal dots in datasets. Single values also accept decimal commas and scientific notation such as 1.2e-3 or 1.2 × 10⁻³.
Calculated locally. No account or input upload.
Result & working
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Interpretation & assumptions
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Formula & example
The relationship
What the variables mean
| Symbol | Meaning |
|---|---|
| Population size. |
Worked example
- Initial population
- 1200
- Final population
- 1500
- Time interval
- 3
- Time unit
- years
100 individuals/years
Follow the example steps
- ΔN = 1500 − 1200 = 300
- average rate = ΔN/Δt = 300/3 = 100 per years
- percentage change = 300/1200 × 100 = 25%
Common mistakes
Distinguish the absolute change from the percentage change.
Incorrect approach
N₀ = 100, N₁ = 120: ΔN = 20%
Correct approach
ΔN = 20; 100 × ΔN/N₀ = 20%
More checks before you submit
- A percentage increase and an absolute increase answer different questions.
Method notes
This is an average over the interval, not an instantaneous logistic-growth model.