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 : https://brainly.com/question/11052356
Keyword : linear function
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