Question

1. the graph below shows the amount of water in a storage tank over several months. this relationship is linear. the tank started with 9,000 gallons. after 5 months, there was 4,000 gallons of water. what is the rate of change (slope)?

Explanation:

Step1: Identify two - point formula

The slope formula for two points $(x_1,y_1)$ and $(x_2,y_2)$ is $m=\frac{y_2 - y_1}{x_2 - x_1}$.

Step2: Determine the two points

The tank starts with 9000 gallons at $x = 0$, so the first point is $(0,9000)$. After 5 months, there is 4000 gallons, so the second point is $(5,4000)$.

Step3: Calculate the slope

$m=\frac{4000 - 9000}{5-0}=\frac{- 5000}{5}=-1000$.

Answer:

$-1000$