Ginny is studying a population of frogs. She determines that the population is decreasing at an average rate of [tex]3\%[/tex] per year. When she began her study, the frog population was estimated at 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 find the function that represents the frog population after [tex]\( x \)[/tex] years, let's go through the necessary steps to understand the problem:

1. Initial Population: The problem states that the initial population of frogs when Ginny began her study was 1,200.

2. Rate of Decrease: The population is decreasing at an average rate of 3% per year.

3. Understanding the Decrease Rate:
- A decrease of 3% per year means that each year the population is 97% of what it was the previous year.
- Mathematically, a 3% decrease implies multiplying the population by [tex]\( 1 - 0.03 = 0.97 \)[/tex] each year.

4. Finding the Function:
- Let the population after [tex]\( x \)[/tex] years be represented by the function [tex]\( f(x) \)[/tex].
- Initially (at [tex]\( x = 0 \)[/tex]), the population is 1200.
- After 1 year, the population is [tex]\( 1200 \times 0.97 \)[/tex].
- After 2 years, the population is [tex]\( 1200 \times 0.97^2 \)[/tex].
- Therefore, after [tex]\( x \)[/tex] years, the population is [tex]\( 1200 \times 0.97^x \)[/tex].

Putting this information together, the function that represents the frog population after [tex]\( x \)[/tex] years is:

[tex]\[ f(x) = 1200 \cdot 0.97^x \][/tex]

From the given options, the correct function is:

[tex]\[ f(x) = 1200(0.97)^x \][/tex]

This matches the option:

[tex]\[ f(x) = 1200(0.97)^x \][/tex]