# Thread: Volume and Surface Area Answer Confirmation

1. ## Volume and Surface Area Answer Confirmation

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

2. Originally Posted by haftakhan

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.

3. 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.

4. 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: . $192 + 168 + 280 + 224 \;=\;864\text{ units}^2$

5. About the rest ?

6. 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.

7. 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?