Ginny is studying a population of frogs. The population is decreasing at an average rate of 3% per year. The initial population was 1,200.

Which function represents the frog population after [tex]\( x \)[/tex] years?

A. [tex]\( f(x) = 1,200(1.03)^x \)[/tex]
B. [tex]\( f(x) = 1,200(0.03)^x \)[/tex]
C. [tex]\( f(x) = 1,200(0.97)^x \)[/tex]
D. [tex]\( f(x) = 1,200(0.97 x) \)[/tex]



Answer :

To determine the correct function that represents the frog population after [tex]\( x \)[/tex] years when the population is decreasing at an average rate of [tex]\( 3\% \)[/tex] per year, we need to follow these steps:

1. Understand the Decrease in Population:
- The population is decreasing at a rate of [tex]\( 3\% \)[/tex] per year. This means that each year, the population retains [tex]\( 100\% - 3\% = 97\% \)[/tex] of its previous year's population.

2. Initial Population:
- When Ginny began her study, the frog population was estimated at 1,200.

3. Formulate the Recursive Model:
- Let the initial population be [tex]\( P_0 = 1200 \)[/tex].
- The population after one year would be [tex]\( P_1 = 1200 \times 0.97 \)[/tex].
- The population after two years would be [tex]\( P_2 = 1200 \times 0.97 \times 0.97 \)[/tex].

4. Generalize to [tex]\( x \)[/tex] Years:
- We can generalize this to say that the population after [tex]\( x \)[/tex] years, [tex]\( P(x) \)[/tex], is given by multiplying the initial population by [tex]\( 0.97 \)[/tex] raised to the power of [tex]\( x \)[/tex]:
[tex]\[ P(x) = 1200 \times (0.97)^x \][/tex]

Therefore, among the given choices, the function that correctly represents the frog population after [tex]\( x \)[/tex] years is:
[tex]\[ f(x) = 1,200 (0.97)^x \][/tex]

So the correct function choice is:
[tex]\[ \boxed{f(x) = 1,200 (0.97)^x} \][/tex]

This corresponds to the third option given in the question.

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