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Math Help - Volume and Surface Area Answer Confirmation

  1. #1
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    Question Volume and Surface Area Answer Confirmation

    Volume and Surface Area Answer Confirmation-showimage.php.jpg

    Here are the answers.

    1)Volume=1344,Area=1168

    2)volume of square=864
    Volume of rectangle=108
    Total Volume=972

    Area of square=720
    Area of rectangle=180
    total surface area=900

    3)Volume of triangle=336
    Area of triangle488

    4)volume=288
    Area=368

    5)??

    6)Total Volume=2520

    Total surface area=1684
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  2. #2
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    Quote Originally Posted by haftakhan View Post

    Here are the answers.

    1)Volume=1344,Area=1168
    I agree with the volume, how did you get the surface area?

    Best show your workings for all problems.
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  3. #3
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    1) Volume: 1344 = Correct, Surface area: 1168 = Incorrect. (Hint: It is under 1000)

    2) Volume: 972 = Correct, Surface area: 900 = Incorrect. (Hint: It is less than 800)

    3) Volume: 336 = Correct, Surface area: 488 = Incorrect.
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  4. #4
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    Hello, haftakhan!

    I have difficulty reading the numbers.
    I'll explain the surface area of the first one.

    Code:
                      *
                  *       *
              *               * 20
          *                       *
          *   *                       *
          *       *                       *
       12 *           *                       *
          *               *                *
          *                   *       *  14
          *  *  *  *  *  *  *  *  *
                     16

    The front face is a right triangle with base 16 and height 12.
    . . Its area is: . \tfrac{1}{2}(16)(12) \:=\:96
    The rear face is identical.
    . . \text{Area(front and rear)} \:=\:2\cdot96 \:=\:192

    The left face is a 14\times12 rectangle.
    . . \text{Area(left)} \;=\;14\cdot12 \;=\;168

    The sloping right face is a 14\times 20 rectangle.
    . . \text{Area(right)} \;=\;14\cdot20 \;=\;280

    The bottom face is a 16 \times 14 rectangle.
    . . \text{Area(bottom)} \;=\;16\cdot14 \:=\:224


    Total surface area: . 192 + 168 + 280 + 224 \;=\;864\text{ units}^2

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  5. #5
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    About the rest ?
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  6. #6
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    4) Volume: 288 = Correct, Surface area: 368 = Incorrect.

    5)
     \mbox{Volume} = 20*3*4 + 4*8*20
    Divide the shape into 3 parts - 2 triangular prisms and 1 rectangular prism.

     \mbox{Surface Area} = 3*4*2 + 4*8*2 + 20*5*2 + 8*20 + 14*20
    Just calculate the surface area of each face and then add them together.

    6) (I'm guessing the depth of this one is 10, it is almost cut off)
    Volume: 2520 = Correct, Surface area: 1684 = Incorrect. (Hint: It is under 1500)


    To me it seems that all of your volume calculations are correct, but your surface area is over what it actually is. How are you working out your surface area? Show ALL of your working so we can tell what you did wrong.
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  7. #7
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    Formula used to fine the surface area =2(L*W+L*H+W*H)


    What are the answers for surface area for the questions 2,3 and 6?
    Last edited by haftakhan; August 21st 2010 at 06:09 PM.
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