Question

a citys population in the year $x = 1998$ was $y = 1,626,800$. in 1979 the population was 1,628,700. compute the slope of the population growth (or decline) and choose the most accurate statement from the following:
the population is increasing at a rate of 200 people per year.
the population is decreasing at a rate of 100 people per year.
the population is increasing at a rate of 100 people per year.
the population is decreasing at a rate of 200 people per year.
the population is increasing at a rate of 250 people per year.
the population is decreasing at a rate of 250 people per year.

Explanation:

Step1: Identify the two - point data

Let $x_1 = 1979$, $y_1=1628700$, $x_2 = 1998$, $y_2 = 1626800$.

Step2: Use the slope formula

The slope formula is $m=\frac{y_2 - y_1}{x_2 - x_1}$. So $m=\frac{1626800 - 1628700}{1998 - 1979}=\frac{- 1900}{19}=- 100$.

Answer:

The population is decreasing at a rate of 100 people per year.