The current fox population in a protected region is 367 and is decreasing by 8 percent per year. Find the exponential function f(x) that represents the fox population, where x is the number of years from now. Estimate the population 9 years from now.

1 answer

To find the exponential function \( f(x) \) that represents the fox population decreasing by 8 percent per year, we start from the initial population and apply the decay formula.

The general form for an exponential decay function is:

\[ f(x) = P_0 \cdot (1 - r)^x \]

where:

  • \( P_0 \) is the initial population,
  • \( r \) is the decay rate (as a decimal),
  • \( x \) is the number of years.

Given:

  • \( P_0 = 367 \) (initial population),
  • \( r = 0.08 \) (8 percent is converted to decimal).

The function becomes:

\[ f(x) = 367 \cdot (1 - 0.08)^x = 367 \cdot (0.92)^x \]

Now, to estimate the fox population 9 years from now, we will substitute \( x = 9 \) into the function:

\[ f(9) = 367 \cdot (0.92)^9 \]

First, we compute \( (0.92)^9 \):

\[ (0.92)^9 \approx 0.4224 \]

Now, multiply this value by the initial population:

\[ f(9) \approx 367 \cdot 0.4224 \approx 155.50 \]

Rounding to the nearest whole number, the estimated fox population 9 years from now is approximately \( 156 \).

Thus, the exponential function representing the fox population is:

\[ f(x) = 367 \cdot (0.92)^x \]

And the estimated fox population 9 years from now is:

\[ \approx 156 \]