Logistic vs Exponential Growth

4
advanced-math

A population follows logistic growth: P(t)=10001+9e0.5tP(t) = \frac{1000}{1 + 9e^{-0.5t}}. What is the carrying capacity?

A

1,000

B

9

C

100

D

500

Correct Answer: A

Choice A is the correct answer. Identify the limiting value.

  1. Logistic form: P(t)=K1+AertP(t) = \frac{K}{1 + Ae^{-rt}} where KK is carrying capacity.
  2. As tt \to \infty: e0.5t0e^{-0.5t} \to 0, so P(t)10001+0=1000P(t) \to \frac{1000}{1 + 0} = 1000.
  3. Carrying capacity: The maximum population is 1,000.

💡 Strategic Tip: In logistic growth, the numerator is always the carrying capacity.

Choice B is incorrect because 9 is the coefficient AA, not the limit. Choice C is incorrect because this is the initial population P(0)=100010=100P(0) = \frac{1000}{10} = 100. Choice D is incorrect because this is half the carrying capacity.