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Math Help - Cuboid

  1. #1
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    Cuboid

    If each side of a cuboid is doubled,its volume is
    (a)doubled
    (b)becomes 4 times
    (c)becomes 6 times
    (d)becomes 8 times
    Last edited by devi; August 24th 2008 at 10:28 PM.
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  2. #2
    is up to his old tricks again! Jhevon's Avatar
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    Quote Originally Posted by devi View Post
    If each side of a cuboid is doubled,its volume is
    (a)doubled
    (b)becomes 4 times
    (c)becomes 6 times
    (d)becomes 6 times
    Let x be the side length of a cuboid.

    the volume is given by:

    V = x^3

    now change x to 2x. what happens to V? how many times larger does it become?
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  3. #3
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    Quote Originally Posted by devi View Post
    If each side of a cuboid is doubled,its volume is
    (a)doubled
    (b)becomes 4 times
    (c)becomes 6 times
    (d)becomes 6 times
    d) becomes 6 times as posted is a typo. It should have been becomes 8 times.

    The answer is d.

    Original volume = a*b*c = abc
    When each side is doubled, new volume = (2a)(2b)(2c) = 8abc.
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  4. #4
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    Quote Originally Posted by ticbol View Post
    d) becomes 6 times as posted is a typo. It should have been becomes 8 times.

    The answer is d.

    Original volume = a*b*c = abc
    When each side is doubled, new volume = (2a)(2b)(2c) = 8abc.
    Yes it is a typo.But the answer was doubled.
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  5. #5
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    Quote Originally Posted by devi View Post
    Yes it is a typo.But the answer was doubled.
    You mean the answer is a)?
    Cannot be.

    A dictionanary says a cuboid is a rectangular parallelepiped. So it looks like any box of six rectangular faces. (A square is also a rectangular, by the way).
    So the volume is length*width*height.
    If all those 3 dimensions are doubled, then the original volume is doubled only according to your book?
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