Jose is considering two different cell phone plans for his son. He is not sure how many minutes he uses each month. Which plan should he choose?

True Sound is offering a cellular phone plan that costs $25 per month for 200 minutes. Any minutes after 200 will cost $0.11 a minute.

Cellular Zone is offering a cellular phone plan that costs $30 per month for 300 minutes. Any minutes after 300 will cost $0.09 a minute.

Question

Jose is considering two different cell phone plans for his son. He is not sure how many minutes he uses each month. Which plan should he choose? 

True Sound is offering a cellular phone plan that costs $25 per month for 200 minutes. Any minutes after 200 will cost $0.11 a minute. 

Cellular Zone is offering a cellular phone plan that costs $30 per month for 300 minutes. Any minutes after 300 will cost $0.09 a minute.

whpalmer4 · Answer

Write the equation for each plan's cost in terms of minutes used.  Set the two equal to each  other and solve for the number of minutes.  That is the point at which both plans are equal cost.  Compare that number with expected use, and choose accordingly.

whpalmer4 · Answer

You'll have two equations for each vendor, one for the part where you are only using the included minutes, and one for the part where you are paying by the minute.  Graphing the equations to find the intersection is another way to approach it.