Question

The monthly cost (in dollars) of a long-distance phone plan is a linear function of the total calling time (in minutes). The monthly cost for 50 minutes of calls is $12.55 and the monthly cost for 102 minutes is $17.23. What is the monthly cost for 101 minutes of calls?

Answer 1

The monthly cost will be $17.14

Step-by-step explanation:

Given that the monthly cost (in dollars) of a long-distance phone plan is a linear function of the total calling time (in minutes) then this can be presented in a table form as;

Time in minutes (x)        Cost in dollars (y)

50                                          $12.55

102                                         $ 17.23

Take the values as ordered pairs to represent coordinates for points that satisfy the linear function

(50,12.55)  and (102,17.23)

Finding the slope of the graph using these points

slope,m=Δy/Δx

m=Δy=17.23-12.55 =4.68

Δx=102-50=52

m=4.68/52 =0.09

Finding the equation of the linear function using m=0.09, and point (50,12.55)

m=Δy/Δx

0.09=y-12.55/x-50

0.09(x-50)=y-12.55

0.09x-4.5=y-12.55

0.09x-4.5+12.55=y

y=0.09x+8.05

So for 101 minutes , the cost will be;

y=0.09*101 +8.05

y=9.09+8.05 = $17.14

Learn More

Linear functions : brainly.com/question/11052356

Keyword : linear function

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