Question

Which of the following is the beststatement about the graph? A-400-minute plan costs $40.B- 100-minute plan costs $10. C- 1000-minute plan costs $110. D- 200-minute plan costs $35.

Answer 1

We have a graph in which we have a graph for a line. The line has a slope.

The slope is (from the graph):

We have the following points:

(0, 10), (100, 20), (200, 30), (300, 40)

$\frac{20-10}{100-0}=\frac{10}{100}=\frac{1}{10}$

We have that, for every 100 minutes, the cost of the plan is $10.

That is why for 0 minutes, we have $10 (initial cost). Then, 100 minutes costs $20, 200 minutes $30, and so forth.

Thus, the best statement about the graph is option B: 100-minute plan costs $10.

It also follows the next line equation:

$y=0.1\cdot x+10\Rightarrow y(100)=0.1\cdot100+10\Rightarrow y=10+10=20$

As you can see, for 100 minutes, we have to pay $20.