1
advanced-math

An island's invasive species population follows P(t)=50001+49e0.4tP(t) = \frac{5000}{1 + 49e^{-0.4t}} where tt is years. What is the initial population?

A

100

B

5,000

C

50

D

2,500

Correct Answer: A

Choice A is the correct answer. Evaluate the logistic function at t=0t=0.

  1. Substitute: P(0)=50001+49e0=50001+49P(0) = \frac{5000}{1 + 49e^0} = \frac{5000}{1 + 49}.
  2. Simplify: P(0)=500050=100P(0) = \frac{5000}{50} = 100.
  3. Result: Initial population is 100.

💡 Strategic Tip: For logistic P(t)=K1+AertP(t) = \frac{K}{1 + Ae^{-rt}}, initial value is K1+A\frac{K}{1+A}.

Choice B is incorrect because this is the carrying capacity, not initial population. Choice C is incorrect because this is 1+A1+A (the denominator at t=0t=0). Choice D is incorrect because this is half the carrying capacity.