8

Set 16: Exponential Functions (Advanced)

Explanation

Answer: A

An investment of $8,000 earns continuous compound interest at 5% annual rate. What is the value after 10 years?

Use: A=PertA = Pe^{rt} where e2.718e \approx 2.718

Continuous vs Annual Compounding

A.

$13,181.23

✓ Correct
B.

$12,000.00

C.

$14,000.00

D.

$13,030.16

Detailed Explanation

Choice A is correct. Choice A is the correct answer. Apply the continuous compound interest formula. 1. Formula: A=PertA = Pe^{rt} where P=8000P = 8000, r=0.05r = 0.05, t=10t = 10. 2. Calculate exponent: rt=0.05×10=0.5rt = 0.05 \times 10 = 0.5. 3. Compute: A=8000e0.5=8000(1.6487)13,181.23A = 8000 e^{0.5} = 8000(1.6487) \approx 13,181.23. 4. Result: After 10 years, the investment is worth $13,181.23. Strategic Tip: Continuous compounding uses base ee, which grows faster than annual compounding. Choice B is incorrect because this assumes simple interest (8000 + 4000). Choice C is incorrect because this calculation is wrong. Choice D is incorrect because this uses annual compounding, not continuous.

Key Steps:

The correct answer is $13,181.23

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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