5

Set 9: Exponential Functions (Advanced)

Explanation

Answer: A

$50,000 in a retirement account earns 6% annually. Assuming no additional deposits, what will it be worth in 30 years?

A.

$287,174.56

✓ Correct
B.

$200,000.00

C.

$150,000.00

D.

$300,000.00

Detailed Explanation

Choice A is correct. Choice A is the correct answer. Calculate long-term growth. 1. Formula: A=50000(1.06)30A = 50000(1.06)^{30}. 2. Calculate: (1.06)305.7435(1.06)^{30} \approx 5.7435, so A287,175A \approx 287,175. 3. Rule of 72: Doubling time ≈ 726=12\frac{72}{6} = 12 years. In 30 years ≈ 2.5 doublings → 50k×22.5283k50k \times 2^{2.5} \approx 283 k ✓. Strategic Tip: Long-term exponential growth can produce dramatic results. Choice B is incorrect because this only quadruples the principal. Choice C is incorrect because this only triples the principal. Choice D is incorrect because the calculation doesn't match.

Key Steps:

The correct answer is $287,174.56

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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