Question

Amy is draining an aquarium. The graph shows the amount of water (in liters) in the aquarium versus time (in minutes)

Answer 1

From the graph, we have the amount of water (in liters) on the y-axis and the time (in minutes) on the x-axis

a)

To obtain the amount of water at zero minutes, we will trace the y-value that corresponds with the value of zero on the x-axis: we will see this to be 270 liters

Therefore, at time zero minutes, the amount of water is 270 liters

b)

We will answer this by picking two points that lie along the straight line and calculate the slope. We pick the points:

`\begin{gathered} (x_1,y_1)=(0,270) \\ (x_2,y_2)=(2,90) \end{gathered}`

We will proceed to calculate the slope as shown below:

`\begin{gathered} slope(m)=(y_2-y_1)/(x_2-x_1) \\ \text{Substitute the values of the variables into the equation, we have:} \\ slope(m)=(90-270)/(2-0) \\ slope(m)=-(180)/(2) \\ slope(m)=-90l\text{/}min \end{gathered}`

The slope is -90 liters per minute.

The negative sign (-) means that as time increases, the amount of water in the aquarium decreases

The water decreases at a rate of 90 liters per minute