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Thread: More word problem help

  1. #1
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    More word problem help

    So my question is-

    A fire has started in a dry open field and is spreading in the form of a circle. If the radius of this circle increases at the rate of 6 feet/ minute express the total area A as a function of time t (in minutes).

    It seems to me that area would = time(6(pi)time^2)
    The answer in the book says the answer is= 36(pi)time^2

    It is not clear to me why the 6 must be squared.
    Help?

  2. #2
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    Re: More word problem help

    I'm a little puzzled why 't' was defined but never used. The variable "time" is quite cumbersone.

    Radius(t) = t*(6 ft/min)

    [tex]Area(t)\;=\;\pi\cdot\left[Radius(t)\right]^{2}\;=\;??[/tex]

    Are you seeing it, yet?
    "Unique Answers Don't Care How You Find Them." - Many may have said it, but I hear it most from me.

  3. #3
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    Re: More word problem help

    Hello, VP1!

    A fire has started in a dry open field and is spreading in the form of a circle.
    If the radius of this circle increases at the rate of 6 feet/minute, express the total area [tex]A[/tex] as a function of time [tex]t[/tex] (in minutes).

    It seems to me that area would be: [tex]A \,=\, 6\pi t^2[/tex]

    The answer in the book says the answer is: [tex]36\pi t^2[/tex]

    It is not clear to me why the 6 must be squared.

    We are told that the radius is a function of time: .[tex]r \,=\,6t[/tex]

    [tex]\text{Therefore: }\;A \;=\;\pi r^2 \;=\;\pi(6t)^2 \;=\;36\pi t^2[/tex]

    I'm the other of the two guys who "do" homework.

  4. #4
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    Re: More word problem help

    Thanks for the quick help. That makes so much sense when it's explained, I just can't see it sometimes when looking at the question.

    I definitely need to do more work with word problems to get more comfortable with them. Does anyone have any good websites that devote some reading to solving word problems?

    Thanks- Todd

  5. #5
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    Re: More word problem help

    The most important work and pratice you can do is learning to WRITE clear and concise definitions at the beginning.
    "Unique Answers Don't Care How You Find Them." - Many may have said it, but I hear it most from me.

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