6

Set 5: Exponential Functions (Advanced)

Explanation

Answer: A

An EV battery's capacity degrades to 80% of original after 1,000 charge cycles. What is the decay factor per cycle?

A.

About 0.9998

✓ Correct
B.

About 0.99

C.

About 0.9995

D.

About 0.98

Detailed Explanation

Choice A is correct. Choice A is the correct answer. Find the decay factor per cycle. 1. Model: C(n)=C0bnC(n) = C_0 b^n where bb is decay factor per cycle. 2. After 1000 cycles: 0.80C0=C0b10000.80C_0 = C_0 b^{1000}. 3. Simplify: 0.80=b10000.80= b^{1000}. 4. Solve: b=(0.80)1/1000=0.800.001b = (0.80)^{1/1000} = 0.80^{0.001}. 5. Calculate: b0.9998b \approx 0.9998 (loses about 0.02% per cycle). Strategic Tip: Small decay per cycle compounds to significant loss over many cycles. Choice B is incorrect because this loses 1% per cycle (too much). Choice C is incorrect because this loses 0.05% per cycle. Choice D is incorrect because this loses 2% per cycle (way too much).

Key Steps:

The correct answer is About 0.9998

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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