SOLUTION: The cost of water(in dollars) is a linear fuction of the amount of water used(in hundreds of cubic feet,HCF). The cost of using 18 HCF is $39.35 and the cost of using 55 HCF is $10

Algebra ->  Coordinate Systems and Linear Equations  -> Lessons -> SOLUTION: The cost of water(in dollars) is a linear fuction of the amount of water used(in hundreds of cubic feet,HCF). The cost of using 18 HCF is $39.35 and the cost of using 55 HCF is $10      Log On


   

Question 205174: The cost of water(in dollars) is a linear fuction of the amount of water used(in hundreds of cubic feet,HCF). The cost of using 18 HCF is $39.35 and the cost of using 55 HCF is $104.10. What is the cost of using 53 HCF of water
Answer by stanbon(75887) About Me  (Show Source):
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The cost of water(in dollars) is a linear fuction of the amount of water used(in hundreds of cubic feet,HCF). The cost of using 18 HCF is $39.35 and the cost of using 55 HCF is $104.10. What is the cost of using 53 HCF of water
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You have two points relating usage and cost.
You want cost to be the dependent variable.
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Points: (18 , 39.35) and (55 , 104.10)
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slope = (104.10-39.35)/(55-18) = 64.15/37 = 1.7338
intercept: 39.35 = 1.7338*18 + b
b = 8.14189
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Equation: cost = 1..7338(use)+8.14189
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cost(53) = 1.7338*53+8.14189 = $100.03
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Cheers,
Stan H.