Example 4 from Algebra and Trigonometry, 4.1 Linear Functions

Finding the Population Change from a Linear Function

The population of a city increased from 23,400 to 27,800 between 2008 and 2012. Find the change of population per year if we assume the change was constant from 2008 to 2012.

Work it out on paper first. Then open the solution one step at a time, and stop as soon as you can finish on your own.

Solution
The rate of change relates the change in population to the change in time. The population increased by $27, 800 - 23, 400 = 4400$ people over the four-year time interval. To find the rate of change, divide the change in the number of people by the number of years.

$\frac{4,400 people}{4 years} = 1,100 \frac{people}{year}$
So the population increased by 1,100 people per year.

Your turn

The book's Try It right after this example: same idea, new numbers. Only the answer is given.

The population of a small town increased from 1,442 to 1,868 between 2009 and 2012. Find the change of population per year if we assume the change was constant from 2009 to 2012.

How did it go?

Solution

Your turn

Solution

Your turn