Question

Bob can choose plan A or Plan B for his long-distance charges. For each plan, (cost in dollars) depends on minutes used (per month) as shown below.If Bob makes 50 mins of long distance calls for the month, which plan costs less?How much less does it cost than the other plan? $For what number of long distance mins do the two plans cost the same? If the time spent on long distance calls is less than this amount, which plan cost more?

Answer 1

If Bob makes 50 mins of long distance calls for the month, We can trace this value to the graphs and connect where it meets the y axis.

- It costs B(50) - A(50) more or less than the other one.

`\begin{gathered} B(50)=8 \\ A(50)=4 \\ B(50)-A(50)=8-4=\text{ \$4} \end{gathered}`

Thus, it is $4 cheaper to work with PLAN B

- This is the position where there is a collision among the graphs

The long distance mins to do the two plans cost the same at the point (150, 12)

Thus, at 150 minutes, both plans cost the same.

- After their meeting point, at any minute used, it is more expensive to subscribe to PLAN A.

This can be clearly inferred to from the graph.