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Math Help - Pre-Calculus Word Problems Help

  1. #1
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    Pre-Calculus Word Problems Help

    So, my teacher recently assigned a few problems for homework that I am completely clueless about.

    I was wondering if somebody could assist me in at least outlining the steps needed to solve the following problem:

    The cost of renting a large boat is 30 dollars per hour plus a usage fee roughly equivalent to x^3 cents per hour when the boat is operated at a speed of x km/h. Express the cost C (in cents per kilometer) as a function of x.
    Thanks
    Last edited by mr fantastic; January 23rd 2010 at 01:38 AM. Reason: Restored original question.
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  2. #2
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    This may not be the best way to go about this, but...

    distance = rate \times time or d=r \times t.

    So if you go d km for t hours, then \frac{d}{t}=r km per hour.

    \left(\frac{d}{t}\right)^3\times t + 3000\times t gives the total cost (in cents) combining the hourly and usage fees, so \frac{\left(\frac{d}{t}\right)^3\times t + 3000\times t}{d} is the total cost per km.

    Since you want to get the cents per 1 km at x km per hour, use the simple distance formula to arrive at: f(x)=\left(x^3+3000\right)\times \frac{1}{x}.

    I'm curious to see how others would solve this problem.
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  3. #3
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    You're welcome, Marko. For future reference, it's better if you don't edit your post to remove the original problem statement. Instead, simply post a new reply. This way others browsing the thread in the future will be able to benefit from it.
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