SOLUTION: I need help figuring out how to solve this problem. The cost C of steel tubing is jointly proportional to its length L, in feet, and Diameter D, in inches. If a 9 foot tube wit

Algebra ->  Polynomials-and-rational-expressions -> SOLUTION: I need help figuring out how to solve this problem. The cost C of steel tubing is jointly proportional to its length L, in feet, and Diameter D, in inches. If a 9 foot tube wit      Log On


   



Question 1109878: I need help figuring out how to solve this problem.
The cost C of steel tubing is jointly proportional to its length L, in feet, and Diameter D, in inches. If a 9 foot tube with a 1 inch diameter cost $72, find the cost of a 9 ft tube with a diameter of 10 inches.

Answer by stanbon(75887) About Me  (Show Source):
You can put this solution on YOUR website!
The cost C of steel tubing is jointly proportional to its length L, in feet, and Diameter D, in inches. If a 9 foot tube with a 1 inch diameter cost $72, find the cost of a 9 ft tube with a diameter of 10 inches.
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C = k*L*D
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Solve for "k"
72 = k*9*1
k = 8
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Equation:
C = 8*L*D
C = 8*9*10 = $720
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Cheers,
Stan H.
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