Math Problem Statement

A town starts with 30,000 residents and grows at a continuous rate of 7% per year.

(a) Write a formula for the population of the town after t years.

(b) What is the population of the town after 8 years have passed?

(c) Find the annual growth rate of the population of the town.

Solution

The town's population growth can be modeled using the formula for continuous exponential growth, which is:

P(t)=P0ertP(t) = P_0 \cdot e^{rt}

where:

  • P(t)P(t) is the population after tt years,
  • P0P_0 is the initial population,
  • rr is the continuous growth rate (as a decimal),
  • tt is the time in years,
  • ee is Euler's number (approximately 2.71828).

(a) Formula for the population of the town after tt years:

Given:

  • Initial population, P0=30,000P_0 = 30,000,
  • Continuous growth rate, r=0.07r = 0.07 (since 7% = 0.07 in decimal form),

The formula for the population after tt years is:

P(t)=30,000e0.07tP(t) = 30,000 \cdot e^{0.07t}

(b) Population after 8 years:

We can use the formula P(t)=30,000e0.07tP(t) = 30,000 \cdot e^{0.07t} to calculate the population after 8 years, where t=8t = 8.

P(8)=30,000e0.078P(8) = 30,000 \cdot e^{0.07 \cdot 8}

Let's calculate this:

P(8)=30,000e0.56P(8) = 30,000 \cdot e^{0.56}

We can now find the exact value of P(8)P(8).

(c) Annual growth rate of the population:

The continuous growth rate given is 7% per year. To find the annual growth rate, we can use the relationship between continuous and annual growth rates:

rannual=ercontinuous1r_{\text{annual}} = e^{r_{\text{continuous}}} - 1

Substituting rcontinuous=0.07r_{\text{continuous}} = 0.07:

rannual=e0.071r_{\text{annual}} = e^{0.07} - 1

Now, I'll compute the exact values for both parts (b) and (c).### (b) Population after 8 years: The population of the town after 8 years is approximately:

P(8)52,520 residentsP(8) \approx 52,520 \text{ residents}

(c) Annual growth rate:

The annual growth rate is approximately:

7.25% per year7.25\% \text{ per year}

Do you want further details or have any questions? Here are five related questions to explore:

  1. How would the population change if the growth rate were 5% instead of 7%?
  2. How long will it take for the population to double at this growth rate?
  3. What is the population after 15 years?
  4. How does continuous growth compare to simple interest growth over 10 years?
  5. How do exponential growth models apply to population dynamics in real-world scenarios?

Tip: For long-term growth predictions, exponential models provide more accuracy, especially for natural growth processes.

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Math Problem Analysis

Mathematical Concepts

Exponential Growth
Continuous Growth Rate
Population Growth Modeling

Formulas

P(t) = P_0 * e^(rt)
r_annual = e^r_continuous - 1

Theorems

Exponential Growth Model

Suitable Grade Level

Grades 10-12