Question

The following graph shows a relationship between the gallons of fuel remaining in a car's gas tank and the number of miles traveled.
Find the equation for the line of best fit given in the below graph.

y= ___ x ___ ___

Choices:
17.2
-0.013
-
-0.06
+
21.15
16.92
-0.04

Answer 1

Y=-0.04x+17.2

This equation matches the point at (30, 16) on the graph, and so I deem this equation as correct.

Answer 2

Answer:

y = -0.04x + 17.2

Explanation:

The y-intercept is the point where the graph crosses the y-axis.  In an equation in slope-intercept form, y=mx+b, it is b, the number added after the x.

Looking at our graph, we can see that the graph intersects the y-axis a little over 17; this means our y-intercept, given our choices, is 17.2.

The slope is the rate of change; in slope-intercept form it is m, the number x is multiplied by.

In our graph, we can see that it goes from a little over 17 to 16 on the y-axis as it goes from 0 to 30 on the x-axis; this makes the slope about 1/30, or 0.03.  The line is decreasing, so the slope must be negative.  The closest match in our options is -0.04.

This makes the equation y = -0.04x + 17.2.