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Math Help - Need help with confirming answers

  1. #1
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    Need help with confirming answers

    Two oil tankers crash in the Pacific ocean. The spreading oil slick has a
    circular shape, and the radius of the circle is increasing at 200
    meters per hour.

    a) Express the radius of the spill, r, as a power function of time, t,
    in hours since the crash.

    b) Express the area of the spill, A, as a power function of time, t.




    For a) would the formula be f(r) = 200t^2?
    For b) would the formula be f(a) = pi(200t)^2?

    Thanks for the help.
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  2. #2
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    Quote Originally Posted by krzyrice View Post
    Two oil tankers crash in the Pacific ocean. The spreading oil slick has a
    circular shape, and the radius of the circle is increasing at 200
    meters per hour.

    a) Express the radius of the spill, r, as a power function of time, t,
    in hours since the crash.

    b) Express the area of the spill, A, as a power function of time, t.




    For a) would the formula be f(r) = 200t^2?
    For b) would the formula be f(a) = pi(200t)^2?

    Thanks for the help.
    a) You should know that D = TV.

    In this case, D is the radius, T is the time, V is the speed.


    So your function is

    r = 200t, where r is measured in metres and t in hours.


    b) You should know that A = \pi r^2

    So A = \pi (200t)^2

    A = 400 \pi t^2.
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  3. #3
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    I thought it was A = 40,000(pi)(t^2) since you have to distribute the power of 2 in pi(200t)^2
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  4. #4
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    Quote Originally Posted by krzyrice View Post
    I thought it was A = 40,000(pi)(t^2) since you have to distribute the power of 2 in pi(200t)^2
    Yes, that's a typo.
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