Math Problem Statement

The rabbit population on an island starts off as 120 and it grows by 15% per year. How long will it take for the rabbit population to reach 5,000?

Solution

This problem involves exponential growth, where the population grows by a fixed percentage each year. The formula for exponential growth is:

P(t)=P0×(1+r)tP(t) = P_0 \times (1 + r)^t

Where:

  • P(t)P(t) is the population after time tt,
  • P0P_0 is the initial population (120 in this case),
  • rr is the growth rate per year (15% or 0.15),
  • tt is the time in years.

We are looking for tt when P(t)=5000P(t) = 5000, so:

5000=120×(1+0.15)t5000 = 120 \times (1 + 0.15)^t

First, divide both sides by 120:

5000120=(1.15)t\frac{5000}{120} = (1.15)^t

41.67=(1.15)t41.67 = (1.15)^t

Now, take the natural logarithm (ln) of both sides:

ln(41.67)=t×ln(1.15)\ln(41.67) = t \times \ln(1.15)

Solving for tt:

t=ln(41.67)ln(1.15)t = \frac{\ln(41.67)}{\ln(1.15)}

Let me calculate this value for tt.It will take approximately 26.69 years for the rabbit population to reach 5,000.

Would you like more details on this calculation or have any questions?

Here are 5 related questions for further exploration:

  1. How would the time change if the growth rate were 10% instead of 15%?
  2. What if the population goal was 10,000 instead of 5,000?
  3. How does the formula change if the growth is compounded monthly instead of yearly?
  4. What would the population be after 10 years at the same growth rate?
  5. How long would it take for the population to double?

Tip: Using logarithms is crucial when solving for time in exponential growth problems.

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Math Problem Analysis

Mathematical Concepts

Exponential Growth
Logarithms

Formulas

P(t) = P_0 * (1 + r)^t
t = ln(P(t)/P_0) / ln(1 + r)

Theorems

Logarithm properties for solving exponential equations

Suitable Grade Level

Grades 10-12