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| Question 295935:  Suppose that the weight (in pounds) of an airplane is a linear function of the total amount of fuel (in gallons) in its tank. When graphed, the function gives a line with a slope of 5.9.
 With 54 gallons of fuel in its tank, the airplane has a weight of 2418.6 pounds. What is the weight of the plane with 26 gallons of fuel in its tank?
 Answer by nerdybill(7384)
      (Show Source): 
You can put this solution on YOUR website! Suppose that the weight (in pounds) of an airplane is a linear function of the total amount of fuel (in gallons) in its tank. When graphed, the function gives a line with a slope of 5.9. With 54 gallons of fuel in its tank, the airplane has a weight of 2418.6 pounds. What is the weight of the plane with 26 gallons of fuel in its tank?
 .
 We know it is a linear function with a slope of 5.9 and they give us one data point:
 (54, 2418.6)
 .
 Plug it into the "point-slope" form of a line:
 y - y1 = m(x - x1)
 y - 2418.6 = 5.9(x - 54)
 y - 2418.6 = 5.9x - 318.6
 y = 5.9x + 2100
 f(x) = 5.9x + 2100 (this is our function)
 .
 Now we can answer:
 What is the weight of the plane with 26 gallons of fuel in its tank?
 f(26) = 5.9(26) + 2100 = 2253.4 pounds
 
 
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