8

Set 17: Exponential Functions (Intermediate)

Explanation

Answer: A

A spacecraft's velocity increases by v(t)=1000e0.05tv(t) = 1000e^{0.05t} m/s where tt is seconds. What is the velocity after 20 seconds?

A.

About 2,718 m/s

✓ Correct
B.

About 2,000 m/s

C.

About 3,000 m/s

D.

About 1,500 m/s

Detailed Explanation

Choice A is correct. Choice A is the correct answer. Evaluate at t=20t = 20. 1. Substitute: v(20)=1000e0.05(20)=1000e1=1000ev(20) = 1000 e^{0.05(20)} = 1000 e^1 = 1000 e. 2. Calculate: 1000×2.718=27181000\times 2.718 = 2718 m/s. Strategic Tip: e1=e2.718e^1 = e \approx 2.718. Choice B is incorrect because this assumes linear growth. Choice C is incorrect because this overestimates the growth. Choice D is incorrect because this is too low.

Key Steps:

The correct answer is About 2,718 m/s

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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