10

Set 4: Exponential Functions (Intermediate)

Explanation

Answer: A

A city's renewable energy adoption follows E(t)=1001+19e0.4tE(t) = \frac{100}{1 + 19e^{-0.4t}} percent where tt is years. What is the long-term adoption limit?

A.

100%

✓ Correct
B.

50%

C.

5%

D.

19%

Detailed Explanation

Choice A is correct. Choice A is the correct answer. Find the carrying capacity. 1. As tt \to \infty: e0.4t0e^{-0.4 t} \to 0. 2. Limit: E()=1001+0=100%E(\infty) = \frac{100}{1 + 0} = 100\%. 3. Result: Maximum adoption is 100%. Strategic Tip: In K1+Aert\frac{K}{1 + Ae^{-rt}}, the numerator KK is always the limit. Choice B is incorrect because 50% would be if K=50K = 50. Choice C is incorrect because this is the initial adoption. Choice D is incorrect because 19 is the coefficient AA, not the limit.

Key Steps:

The correct answer is 100%

Why others are wrong:
B: Choice B is incorrect and may result from a calculation error.
C: Choice C is incorrect and may result from a calculation error.
D: Choice D is incorrect and may result from a calculation error.

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