1

Set 9: Exponential Functions (Intermediate)

Explanation

Answer: B

The value of a machine is V(t)=10000(0.8)tV(t) = 10000(0.8)^t. What is the rate of depreciation?

A.

80%

B.

20%

✓ Correct
C.

0.8%

D.

0.2%

Detailed Explanation

Choice B is correct. Choice B is the correct answer. Find rr from b=1−rb = 1 - r. 1. Identify Factor: b=0.8b = 0.8. 2. Solve for r: 0.8=1−r  ⟹  r=0.20.8= 1 - r \implies r = 0.2. 3. Convert: 0.2=20%0.2= 20\%. Strategic Tip: If you keep 80%, you lost 20%. Choice A is incorrect because 80% is what remains. Choice C is incorrect because it confuses decimal places.

Key Steps:

•

The correct answer is 20%

Why others are wrong:
A: Choice A 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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