Answer:
23,333 kg
Explanation:
G(t) = 30,000 e^(-0.6 t) / (1 + 5 e^(-0.6 t))²
The change in the biomass between 2000 and 2020 is:
∫₀²⁰ G(t) dt
∫₀²⁰ 30,000 e^(-0.6 t) / (1 + 5 e^(-0.6 t))² dt
If u = 1 + 5 e^(-0.6 t), then:
du = -3 e^(-0.6 t) dt
-10,000 du = 30,000 e^(-0.6 t) dt
∫ (-10,000 / u²) du
-10,000 ∫ u⁻² du
10,000 u⁻¹ + C
10,000 / (1 + 5 e^(-0.6 t)) + C
Evaluate between t=0 and t=20.
10,000 / (1 + 5 e^(-0.6 × 20)) − 10,000 / (1 + 5 e^(-0.6 × 0))
10,000 / (1 + 5 e^(-12)) − 10,000 / 6
≈ 8333
The biomass increases by 8,333 kg. So the final biomass is 23,333 kg.