Finding the Population at a Given Time

Oct 13, 2025 by wbrum.org 80 views

Introduction

The population of a city can be modeled using various mathematical equations, each representing a different aspect of population growth. In this article, we will focus on the formula $P=100,000 \cdot 10^{0.02t}$ , where $t$ is the number of years after 2012 and $P$ is the city's population. This equation is a classic example of an exponential growth model, which is commonly used to describe population growth in cities.

Understanding the Formula

The formula $P=100,000 \cdot 10^{0.02t}$ can be broken down into two main components:

Initial Population: The initial population of the city is represented by the constant $100,000$ . This is the population of the city in the year 2012.
Growth Rate: The growth rate of the population is represented by the exponent $0.02t$ . This represents the rate at which the population is increasing over time.

Analyzing the Growth Rate

The growth rate of the population is represented by the exponent $0.02t$ . This means that the population is increasing at a rate of $2\%$ per year. This is a relatively slow rate of growth, but it is still significant and can have a major impact on the city's infrastructure and resources.

Finding the Population at a Given Time

To find the population of the city at a given time, we can plug in the value of $t$ into the formula. For example, if we want to find the population of the city in the year 2020, we can plug in $t=8$ into the formula:

P=100,000 \cdot 10^{0.02(8)}

Simplifying the equation, we get:

P=100,000 \cdot 10^{0.16}

Using a calculator to evaluate the expression, we get:

P=100,000 \cdot 1.1733

P=117,330

Therefore, the population of the city in the year 2020 is approximately $117,330$ .

Finding the Time Required to Reach a Given Population

To find the time required to reach a given population, we can rearrange the formula to solve for $t$ . For example, if we want to find the time required to reach a population of $150,000$ , we can set up the equation:

150,000=100,000 \cdot 10^{0.02t}

Dividing both sides by $100,000$ , we get:

1.5=10^{0.02t}

Taking the logarithm of both sides, we get:

\log(1.5)=\log(10^{0.02t})

Using the property of logarithms that $\log(a^b)=b\log(a)$ , we can simplify the equation to:

\log(1.5)=0.02t\log(10)

Simplifying further, we get:

\log(1.5)=0.02t

Dividing both sides by $0.02$ , we get:

t=\frac{\log(1.5)}{0.02}

Using a calculator to evaluate the expression, we get:

t=34.64

Therefore, it will take approximately $34.64$ years for the population of the city to reach $150,000$ .

Conclusion

In conclusion, the formula $P=100,000 \cdot 10^{0.02t}$ can be used to model the population of a city over time. By analyzing the growth rate and using the formula to find the population at a given time or the time required to reach a given population, we can gain a better understanding of the city's population dynamics. This can be useful for city planners and policymakers who need to make informed decisions about the city's infrastructure and resources.

References

[1] Population Growth Models. (n.d.). Retrieved from https://www.mathsisfun.com/algebra/population-growth-models.html
[2] Exponential Growth. (n.d.). Retrieved from https://www.khanacademy.org/math/algebra2/x2f2f4f/exponential-growth-and-decay/v/exponential-growth

Glossary

Exponential Growth: A type of growth where the rate of growth is proportional to the current value.
Growth Rate: The rate at which the population is increasing over time.
Initial Population: The population of the city in the year 2012.
Population: The number of people living in a city.
Time: The number of years after 2012.
The Population of a City: Modeling and Analysis - Q&A =====================================================

Introduction

In our previous article, we discussed the formula $P=100,000 \cdot 10^{0.02t}$ , which can be used to model the population of a city over time. In this article, we will answer some frequently asked questions about the formula and its applications.

Q&A

Q: What is the initial population of the city?

A: The initial population of the city is represented by the constant $100,000$ . This is the population of the city in the year 2012.

Q: What is the growth rate of the population?

A: The growth rate of the population is represented by the exponent $0.02t$ . This means that the population is increasing at a rate of $2\%$ per year.

Q: How can I find the population of the city at a given time?

A: To find the population of the city at a given time, you can plug in the value of $t$ into the formula. For example, if you want to find the population of the city in the year 2020, you can plug in $t=8$ into the formula:

P=100,000 \cdot 10^{0.02(8)}

Simplifying the equation, you get:

P=100,000 \cdot 10^{0.16}

Using a calculator to evaluate the expression, you get:

P=100,000 \cdot 1.1733

P=117,330

Therefore, the population of the city in the year 2020 is approximately $117,330$ .

Q: How can I find the time required to reach a given population?

A: To find the time required to reach a given population, you can rearrange the formula to solve for $t$ . For example, if you want to find the time required to reach a population of $150,000$ , you can set up the equation:

150,000=100,000 \cdot 10^{0.02t}

Dividing both sides by $100,000$ , you get:

1.5=10^{0.02t}

Taking the logarithm of both sides, you get:

\log(1.5)=\log(10^{0.02t})

Using the property of logarithms that $\log(a^b)=b\log(a)$ , you can simplify the equation to:

\log(1.5)=0.02t\log(10)

Simplifying further, you get:

\log(1.5)=0.02t

Dividing both sides by $0.02$ , you get:

t=\frac{\log(1.5)}{0.02}

Using a calculator to evaluate the expression, you get:

t=34.64

Therefore, it will take approximately $34.64$ years for the population of the city to reach $150,000$ .

Q: What are some real-world applications of this formula?

A: This formula can be used in a variety of real-world applications, such as:

Urban planning: By using this formula to model population growth, urban planners can make informed decisions about the city's infrastructure and resources.
Economic development: By understanding the population growth of a city, businesses and investors can make informed decisions about where to locate and how to allocate resources.
Public health: By understanding the population growth of a city, public health officials can make informed decisions about how to allocate resources and provide services.

Q: What are some limitations of this formula?

A: While this formula is a useful tool for modeling population growth, it has some limitations. For example:

Assumes constant growth rate: This formula assumes that the growth rate of the population is constant over time, which may not be the case in reality.
Does not account for external factors: This formula does not account for external factors that may affect population growth, such as changes in birth rates or death rates.
May not be accurate for small populations: This formula may not be accurate for small populations, as the growth rate may be affected by random fluctuations.

Conclusion

In conclusion, the formula $P=100,000 \cdot 10^{0.02t}$ is a useful tool for modeling population growth in cities. By understanding the initial population, growth rate, and time required to reach a given population, we can gain a better understanding of the city's population dynamics. While this formula has some limitations, it can be a useful tool for urban planners, economists, and public health officials.

References

[1] Population Growth Models. (n.d.). Retrieved from https://www.mathsisfun.com/algebra/population-growth-models.html
[2] Exponential Growth. (n.d.). Retrieved from https://www.khanacademy.org/math/algebra2/x2f2f4f/exponential-growth-and-decay/v/exponential-growth

Glossary

Exponential Growth: A type of growth where the rate of growth is proportional to the current value.
Growth Rate: The rate at which the population is increasing over time.
Initial Population: The population of the city in the year 2012.
Population: The number of people living in a city.
Time: The number of years after 2012.