The population of an endangered species was estimated to be 240 in 2018. The population has been tracked each year and has been modeled with the geometric sequence 240, 360, 540, 810, . . . . Create a function that models this situation.(1 point) Responses f(n)=240(32)n−1 f left parenthesis n right parenthesis equals 240 left parenthesis Start Fraction 3 over 2 End Fraction right parenthesis superscript n minus 1 baseline f(n)=240(12)n−1 f left parenthesis n right parenthesis equals 240 left parenthesis Start Fraction 1 over 2 End Fraction right parenthesis superscript n minus 1 baseline f(n)=240(120)n−1 f left parenthesis n right parenthesis equals 240 left parenthesis 120 right parenthesis superscript n minus 1 baseline f(n)=240+(n−1)12

1 answer

To model the population of the endangered species using a geometric sequence, we start by identifying the first term and the common ratio.

The given population values are:

  • Year 0 (2018): \(240\)
  • Year 1 (2019): \(360\)
  • Year 2 (2020): \(540\)
  • Year 3 (2021): \(810\)

We can see that each term can be obtained from the previous term by multiplying by a common ratio.

To find the common ratio (r), we can divide the second term by the first term:

\[ r = \frac{360}{240} = 1.5 \]

Also, check the ratio between the second and third terms:

\[ r = \frac{540}{360} = 1.5 \]

And the ratio between the third and fourth terms:

\[ r = \frac{810}{540} = 1.5 \]

Thus, the common ratio \(r\) is indeed \( \frac{3}{2} \) (or 1.5).

The general formula for a geometric sequence is given by:

\[ f(n) = a \cdot r^{(n-1)} \]

where:

  • \(a\) is the first term,
  • \(r\) is the common ratio,
  • \(n\) is the term number.

In this case:

  • \(a = 240\)
  • \(r = \frac{3}{2}\)

Thus, the function that models this situation is:

\[ f(n) = 240 \left( \frac{3}{2} \right)^{(n-1)} \]

Among the provided options, the correct response is:

f(n) = 240(32)^{n-1}

This option seems to contain a typographical error for the common ratio; it should correctly indicate \( \frac{3}{2} \) instead of showing \( 32 \).

Hence, the modeled function should be confirmed as:

f(n) = 240(1.5)^{(n-1)} or f(n) = 240\left(\frac{3}{2}\right)^{(n-1)} (which is the mathematically accurate statement of the sequence).

As none of the provided options are exactly correct, you can clarify or correct them based on the correct parameters discussed.