Q:

Determine whether the graph represents a proportional relationship. A graph is shown. The x-axis is labeled from 0 to 9. The y-axis is labeled from 0 to 15. Four points are shown on the graph on ordered pairs 0, 2 and 1, 6 and 2, 10 and 3, 12. These points are joined by a line. The label on the x-axis is Number of cars. The title on the y-axis is Number of wheels. Yes, it is a proportional relationship because the graph goes through the origin Yes, it is a proportional relationship because the graph is a straight line No, it is not a proportional relationship because the graph is not a straight line No, it is not a proportional relationship because the graph does not go through the origin

Accepted Solution

A:
Take a look at the possible answers and see if any make sense.

Yes, it is a proportional relationship because the graph goes through the origin
* Sorry, but the line you mentioned DOES NOT go through the origin. So this can't be the answer.

Yes, it is a proportional relationship because the graph is a straight line
* The line isn't a straight line. The slope between points (0,2) and (1,6) is 4. The slope between (1,6) and (2,10) is 4. But the slope between (2,10) and (3,12) is 2. So the line isn't straight. So this too is the wrong answer.
That right there eliminates half the choices because those choices describe things that are NOT in the graph you've been given. Now you have to think for which of the two remaining choices are correct.

No, it is not a proportional relationship because the graph is not a straight line
* This is true. The graph for a proportional relationship is a straight line that passes through the origin. And the points you specified are not for a straight line.

No, it is not a proportional relationship because the graph does not go through the origin
* And this too is true. The line doesn't pass through the origin. And as mentioned above, the graph of a proportional relationship is a STRAIGHT line and passes through the origin.

My personal opinion is that you mistyped, or misread something about the problem and because of that, it's currently impossible to determine which of the last 2 options is the correct one. I suspect the last ordered pair should be 3,14 and not the 3,12 you've entered. Reason for that is the slope is OK for points 1 through 3, but the 4th point is an outlier. If that's the error, then the correct answer is the last option.