Question

A freight train is carrying goods across the country. The distance it has traveled directly with the number of gallons of fuel it has used. See the graph below

Answer 1

1) To find how many miles per gallon that freight train makes is to find a rate. We can find it in two ways, either by setting a proportion or by finding the slope.

2) Note that this direct variation depicted by the graph is proportional. Therefore, let's find the slope by picking two points:

`\begin{gathered} (200,50),(400,100) \\ \\ m=(y_2-y_1)/(x_2-x_1)=(100-50)/(400-200)=(50)/(200)=(1)/(4) \end{gathered}`

3) Thus, the answers are: