Math Problem Statement

In 2000, the population of a country was approximately 6.07 million and by 2084 it is projected to grow to 14 million. Use the exponential growth model A = A0 * e^(kt), in which t is the number of years after 2000 and A0 is in millions, to find an exponential growth function that models the data. By which year will the population be 12 million?

Solution

Let's solve the problem described in the image. Here is the step-by-step process:

a. Find the exponential growth function

The exponential growth model is given as: A(t)=A0ektA(t) = A_0 e^{kt} where:

  • A0=6.07A_0 = 6.07 (population in millions in the year 2000),
  • A(t)=14A(t) = 14 (population in millions in the year 2084),
  • t=84t = 84 (since 2084 - 2000 = 84 years).

We need to find kk, the growth rate.

Step 1: Use the formula with given data

14=6.07ek8414 = 6.07 e^{k \cdot 84}

Step 2: Solve for kk

Divide both sides by 6.076.07: 146.07=e84k\frac{14}{6.07} = e^{84k} 2.305e84k2.305 \approx e^{84k}

Take the natural logarithm of both sides: ln(2.305)=84k\ln(2.305) = 84k k=ln(2.305)84k = \frac{\ln(2.305)}{84}

Using a calculator: ln(2.305)0.8347\ln(2.305) \approx 0.8347 k0.8347840.00993k \approx \frac{0.8347}{84} \approx 0.00993

So, the growth rate is approximately: k0.00993k \approx 0.00993

The exponential growth function:

A(t)=6.07e0.00993tA(t) = 6.07 e^{0.00993t}


b. Find the year when the population reaches 12 million

We now solve for tt when A(t)=12A(t) = 12: 12=6.07e0.00993t12 = 6.07 e^{0.00993t}

Step 1: Solve for e0.00993te^{0.00993t}

Divide both sides by 6.076.07: 126.07=e0.00993t\frac{12}{6.07} = e^{0.00993t} 1.977e0.00993t1.977 \approx e^{0.00993t}

Step 2: Take the natural logarithm

ln(1.977)=0.00993t\ln(1.977) = 0.00993t t=ln(1.977)0.00993t = \frac{\ln(1.977)}{0.00993}

Using a calculator: ln(1.977)0.683\ln(1.977) \approx 0.683 t0.6830.0099368.8t \approx \frac{0.683}{0.00993} \approx 68.8

Step 3: Add tt to the base year (2000)

2000+68.820692000 + 68.8 \approx 2069


Final Answers:

a) The exponential growth function is: A(t)=6.07e0.00993tA(t) = 6.07 e^{0.00993t}

b) The population will reach 12 million in the year 2069.

Would you like further details or have any questions? Here are some related questions to explore:

  1. How can you graph this exponential function?
  2. What happens to the population after 2084 according to the model?
  3. How does changing the value of A0A_0 or kk affect the growth model?
  4. What are the assumptions made in this exponential model?
  5. Can the model predict a maximum population limit for the country?

Tip: Always double-check exponential models for accuracy by substituting known values to verify the function.

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Math Problem Analysis

Mathematical Concepts

Exponential Growth
Logarithmic Functions
Population Modeling

Formulas

Exponential growth function: A(t) = A0 * e^(kt)
Natural logarithm to solve for growth rate: ln(A/A0) = kt

Theorems

Properties of exponential and logarithmic functions

Suitable Grade Level

Grades 10-12