Can you connect the points with one straight line that passes through the origin?
Frank's plan is proportional, see solution.
Practice makes perfect
Before we begin, let's take a look at the information given in the table of values.
Cell Phone Plans
Time (min)
Frank's Cost ($)
Allie's Cost ($)
0
0
4.00
3
1.50
4.50
6
3.00
5.00
To know if the data given in the table represents a proportional relationship, let's first plot the points as (x,y) coordinate pairs. We will use red points to represent Frank's plan and blue points to represent Allie's plan.
Next, we will connect the points we graphed and extend the line to the y-axis. Recall that the graph of a proportional relationship is a single, straight line in the coordinate plane that passes through the origin.
As we can see, the red line passes through the origin and is a straight line. The blue line does not pass through the origin. Therefore, Frank's cost is proportional to the number of minutes the phone is used.
