5

Set 16: Exponential Functions (Intermediate)

Explanation

Answer: A

$20,000 is borrowed at 9% annual interest compounded monthly. How much is owed after 5 years if no payments are made?

A.

$31,423.48

✓ Correct
B.

$29,000.00

C.

$30,772.48

D.

$35,000.00

Detailed Explanation

Choice A is correct. Choice A is the correct answer. Apply monthly compounding to the loan. 1. Values: P=20000P = 20000, r=0.09r = 0.09, n=12n = 12, t=5t = 5. 2. Formula: A=20000(1+0.0912)60=20000(1.0075)60A = 20000(1 + \frac{0.09}{12})^{60} = 20000(1.0075)^{60}. 3. Calculate: (1.0075)601.57117(1.0075)^{60} \approx 1.57117, so A31,423.48A \approx 31,423.48. Strategic Tip: Monthly rate = 0.0912=0.0075\frac{0.09}{12} = 0.0075, number of periods = 5×12=605\times 12 = 60. Choice B is incorrect because this assumes simple interest. Choice C is incorrect because this uses quarterly compounding. Choice D is incorrect because the calculation is wrong.

Key Steps:

The correct answer is $31,423.48

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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