5

Set 9: Exponential Functions

Explanation

Answer: C

In the function V(t)=2500(1.08)tV(t) = 2500(1.08)^t, which describes the value of an investment over time, what does the number 1.08 represent?

A.

The initial investment was $1.08.

B.

The investment grows by $1.08 each year.

C.

The investment grows by 8% each year.

✓ Correct
D.

The investment grows by 108% each year.

Detailed Explanation

Choice C is correct. Choice C is the correct answer. The base 1.0808 indicates the percentage growth rate. 1. Analyze Base: The growth factor is b=1.08b = 1.08. 2. Find Rate: Since b=1+rb = 1 + r, we have 1.08=1+r1.08= 1 + r, so r=0.08r = 0.08. 3. Convert to %: 0.08=8%0.08= 8\%. Strategic Tip: To find the percentage rate from the factor 1.XX1.XX, just look at the decimal part XXXX. Choice A is incorrect because the initial investment is 2500. Choice B is incorrect because exponential growth is by a percentage, not a fixed dollar amount. Choice D is incorrect because 108% growth would mean b=2.08b = 2.08.

Key Steps:

The correct answer is The investment grows by 8% each year.

Why others are wrong:
A: Choice A is incorrect and may result from a calculation error.
B: Choice B 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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