Now-Next and Population Models

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# Now-Next and Population Models - PowerPoint PPT Presentation

Now-Next and Population Models. Please view this tutorial and answer the follow-up questions on loose leaf to turn in to your teacher. Example.

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### Now-Next and Population Models

Please view this tutorial and answer the follow-up questions on loose leaf to turn in to your teacher.

Example

In 2000, India had a population of about 1.1 billion people. At that time, India’s net growth rate (or net change due to births and deaths) was 2.1% per year. Find India’s population in 2001. Write a Now-Next equation to model India’s population.

The first thing we need to do is find the important information in the problem.

Example

In 2000, India had a population of about 1.1 billion people. At the time India’s net growth rate was 2.1% per year. Find India’s population in 2001. Write a now-next equation to model India’s population.

1.1 billion people.

What is our starting population?

In 2000, the starting population was 1.1 billion people.

Example

In 2000, India had a population of about 1.1 billion people. At the time India’s net growth rate was 2.1% per year. Find India’s population in 2001. Write a now-next equation to model India’s population.

net

growth rate was 2.1%

How is the population changing from year to year?

The population will increase by 2.1% each year.

Example

Important Info: India

2000 population: 1.1 billion

Net Change: 2.1%

Now that we have our important information, we can find the population in 2001.

First we need to find the net change due to births and deaths.

Net change = .021*1.1

= .0231

Example

Important Info: India

2000 population: 1.1 billion

Net Change: 2.1%

Now that we have our important information, we can find the population in 2001.

Next, we need to add this net change to the original population.

New population =

1.1 + .0231

Example

Important Info: India

2000 population: 1.1 billion

Net Change: 2.1%

Now that we have our important information, we can find the population in 2001.

Next, we need to add this net change to the original population.

New population =

1.1231 billion

Example

Important Info: India

2000 population: 1.1 billion

Net Change: 2.1%

Let’s combine the two steps.

New population =

1.1

+

.021

1.1

*

Example

Important Info: India

2000 population: 1.1 billion

Net Change: 2.1%

Now we can replace the things that are changing in the problem with the words NOW and NEXT.

New population =

1.1

+

.021

1.1

*

Example

Important Info: India

2000 population: 1.1 billion

Net Change: 2.1%

NEXT will replace the new population (or the value we are solving for).

New population =

Next =

1.1

+

.021

1.1

*

Example

Important Info: India

2000 population: 1.1 billion

Net Change: 2.1%

We will replace our initial population with the word NOW.

Next =

Now

1.1

+

.021

Now

1.1

*

Example

Important Info: India

2000 population: 1.1 billion

Net Change: 2.1%

You’ll also need to include your starting value, or Now-Start.

Next =

Now

+

.021

Now

*

Now-Start = 1.1 billion

Making Tables

Once you have your equation, you can easily make tables.

Next = Now + .021*Now N.S. = 1.1 billion

Type in your initial population then hit ENTER.

Making Tables

Once you have your equation, you can easily make tables.

Next = Now + .021*Now N.S. = 1.1 billion

Then enter your Now-Next equation by replacing Now with Ans (2nd Negative Sign) then hit ENTER.

Follow-Up Questions

Answer the following questions on loose leaf

and hand them in to your teacher.

Follow-Up Questions

The population of Egypt in 2009 is 77.6 million. The growth rate is 1.68%.

Find the population of Egypt in 2010 and 2011.

Write a Now-Next equation to model the population of Egypt.

When will the population reach 100 million?