Question

Suppose that the monthly cost of a long-distance phone plan (in dollars) is a linear function of the total calling time (in minutes). When graphed, the function

gives a line with a slope of 0.11. See the figure below.
The monthly cost for 34 minutes of calls is $12.62. What is the monthly cost for 25 minutes of calls?

Answer 1

11.63

Explanation:

Since the equation is linear you can find the value by multiplying the difference of the minutes by 0.11, and subtract it from the cost of the initial plan.

34-25=9

9(0.11)= 0.99

12.62-0.99= 11.63