## Monday, January 31, 2011

### Math Test Answers # 2 and 4

Hey Guys :)

Here are the answers for numbers 2 and 4 from our Math Test today.

* I didn't have time to copy the actual picture from our test because I was quite rushing*

1)

So, we were asked to find the Total Surface Area of the given Triangular Prism.

2)

For this number, we were asked to find the Total Surface Area for the given Rectangular Prism.
If you still had problems with finding the T.S.A of a Rectangular or Triangular Prism, here are some links and videos to help you out!
Videos!

If you spot any mistakes, fell free to tell me!

Cylinder Volume and Volume Problems

Chapter 7.3

Formula used : V = pi .r.r.h

a ) v = pi.r.r.h
= 3.14 ( 5.5.23)
= 3.14 ( 575)
= 1805.5 cm3

b) V = pi.r.r.h
= 3.14 ( 14.14.12)
= 3.14( 2352)
= 7385.28 cm 3

c) V = pi.r.r.h
=3.14 ( 0.5.0.5. 1.5)
=3.14 (0.375)
=1.1775 m3

Chapter 7.4

I first tried to find out the volume of the First cylinder,
R= diameter divided by 2
=10 divided by 2
= 5cm 2

V = pi.r.r.h
=3.14 (5.5.30)
=3.14 (750)
=2355 cm 2

I then tried to find out the volume of the Second cylinder without the height

Volume= 2335 cm2
height = pi.r.r
=3.14 (4.4)
=3.14 (16)
=50.24 cm2

I then divided the volume of the 2 cylinders to get the height for the second cylinder,
2335 divided by 50.24
= 46.9 cm3

Video Post

### Volume Scribe Post

Hi! These were the answers to questions #1 and #3 on our math test today!

If the pictures above still leave you confused with surface area, check out these sites :

Feel free to make any changes or comments on my post. Okay bye :)

Cylinder Volume and Volume Problems

## Thursday, January 27, 2011

### Homework Book Page 52-55

Questions: #2 on page 54, #4 on page 55 & #6 on page 55.

2) I was asked to find the surface area of this.
A)
My solution is :

lxw= a
3.2x11.5= 36.8cm²
3.2x11.5= 36.8cm²
5x11.5=57.5cm²
5x11.5=57.5cm²
5x3.2=16cm²
5x3.2=16cm²

TSA= (36.8X2)+(57.5X2)+(16X2)
TSA=220.6cm²

B)

My solution:
lxw=a
4.5x10.4=46.8 cm²
4.5x10.4=46.8 cm²
12x10.4=124.8 cm²
12x10.4=124.8 cm²
12x4.5=54 cm²
12x4.5=54 cm²

TSA=(46.8x2)+(124.8x2)+(54x2)
TSA= 451.2 cm²

4) Ty is painting this storage bench for the deck. How much area does he need to paint, to the nearest hundredth of a square meter?

My solution:
lxw=a
0.5x1.56=0.78m²
0.5x1.56=0.78m²
0.38x1.56=0.5928m²
0.38x1.56=0.5928m²
0.5x0.38=0.19m²
0.5x0.38=0.19m²

TSA=(0.78X2)+(0.5928X2)+(0.19x2)
TSA=3.1256m²

6) A)Calculate the amount of material hey need to make a new cover.

My solution:
TSA= 2.992+2.992+0.88+0.88
TSA= 7.744m²

B) Waterproof material at the Fabric Warehouse is on sale this week for \$24.95 per square metre. Calculate the cost to make he new cover.

Solution:
7.774 X 24.95= 193.96
The cost to make a new cover is \$193.96.

VIDEOS!:)

What is a surface area?

What is the total surface of a triangular prism?
* Photos aren't as clear as always. The camera I'm using often isn't available to use.
___________________________
VOLUME PROBLEMS

r=d/2 The maximum volume is 3.925m³
r=0.5/2
r=0.25m

V=Ï€.r.r.h
V= 3.14 x 0.25 x O.25 x 20
V=0.19625m² x 20m
V=3.925m³
____________________
CYLINDER VOLUME

r=d/2 r=d/2
r=1/2 r=0.8/2
r=0.5m r=0.4m

V=Ï€.r.r.h V=Ï€.r.r.h
V=3.14x0.5 x0.5 x 10 V=3.14x0.4 x0.4 x 10
V=0.785m²x 10m V=0.5024m²x 10
V= 7.85m³ V=5.024

7.85m³-5.024m³=2.826m³ The required concrete is 2.826m³ or 2.8m³

VOLUME VIDEO! ENJOY!:)

### HWB 5.3 Surface Area of a Prism

Okay hi. :) The questions I did were on page 54 and 55. Numbers 2, 3, and 4. Please tell me if I have done something wrong in my work.. and don't make fun of my layout.

2. Calculate the surface area of each rectangular prism to the
nearest tenth of a centimetre squared?

3. Find the surface area of each triangular prism to the nearest tenth of a meter squared.

4. Ty is painting this storage bench for the desk. How much area
does he need to paint, to the nearest hundredth of a square metre?

Volume of a cylinder 03/01/11

a) v= Ï€.r.r.h
v= (3.14.5.5).23
v= 1805.5 cm^

b) v= Ï€.r.r.h
v= (3.14.14.14).12
v=7385.28cm^

Solving Problems using prisms and cylinders
03/01/11

a) He has enough squares. (16 squares)

### Homework Book Page 52-55

My scribe post includes the questions : 4 on page 53 . 2 on page 54 . 4 on page 55 .

Question 4 Page 53
Draw at least four possible nets for a cube. (Each net must fold to create a cube)

Question 2 Page 54
Find the Surface area of the 3-D object
First, you must find the dimensions of the top, front, and side. You then multiply them by each other, as shown below. After you do that, you must add the products together, giving you the total surface area of 220.6cmsquared, 3.14msquared or 451.2cmsquared

Question 4 Page 55
Find the surface area of 3-D object

How many faces does a rectangular prism have?
Create your own poll at Flisti.com

Cylinder Volume and Volume problems

The height to the nearest centimetre is 3.13. To get to this answer, you must divide the volume of the cylinder, by the area of its base, giving you the answer-- which is the height of the cylinder.

The answer to this question is 2.826cm^3.
To get this answer, you must find the area of both of the cylinders, like so. After you find both the areas, you subtract the cylinder that is on the outside, by the cylinder in the inside. You then have your answer.

## Wednesday, January 26, 2011

### Page 180-181 Questions Number 2,4,6, and 8

QUESTIONS:

2. A right rectangular prism has six faces. Why might you have to find the area of only three of the faces to be able to find the surface area? Use pictures and words to explain your thinking.

4. Find the surface area of this CD case.

6. Cheese is sometimes packaged in a triangular box. How much cardboard would you need to cover this piece of cheese if you do not include overlapping? Calculate your answer to the nearest tenth of a square centimeter.

8. Paco builds a glass greenhouse.

a) How many glass faces does the greenhouse have?

b) How much glass does Paco need to buy?

:

2.) I only need to find 3 faces instead of 6 to be able to find the surface area because rectangular prisms share sides. 2 tops, 2 sides, and 2 fronts.

4.) First, you have to find the length and width of each views. For the top view, it's 1cm x 12.3cm, there's 2 top views so it would be 1cm x 12.3 on the other side too. Front view is 14 cm x 12.3 cm, same as the other side. Side view is 14 cm x 1 cm, same as the other side.

6.) A triangular prism has 2 triangles and 3 rectangles.First, we have to find the length and width of the triangles,or rectangles (which ever way you want to start it).We have to use the formula.For rectangle, the formula is b x h =n.The formula for the triangle is b x h divided by 2=n.

8.) Do the steps shown in number 6.
a.) There are 4 glass faces that a greenhouse have.
b.) Paco needs 6.36 m
2.

What is the rectangular prism's formula?

How many faces does a triangular prism have?

Here are some videos you may want to check out:

HERE ARE SOME LINKS YOU MAY WANT TO CHECK OUT:

http://www.math.com/tables/geometry/surfareas.htm
http://easycalculation.com/area/learn-rectangular-prism.php
http://www.aaamath.com/geo.html

GAMING SITES:

http://www.shodor.org/interactivate/activities/
http://www.gamequarium.com/math.htm

QUESTION:

(page 266 #8)

150 cm^3 divided by 48cm^2 = 3.125 cm^2
or = 3 cm^2

Simple Sentence: The height of the cylinder to the nearest centimetre is 3 cm^2.

QUESTION:
(page 273 #3)

V = (b x h / 2) x h
V = (1.4 x 1.7 / 2) x 1.18
V = 1.19 x 1.18
V = 1.4042 m^3

1.7 x 4 = 6.8 m <---- Height
1.4 x 4 = 5.6 m <---- Length

a) Yes, he has enough small prisms.

b) 1.4042 m^3 x 16 = 22.4672 m^3 or 22.47 m^3
The volume of the new prism to the nearest hundredths of a metre is 22.47 m^3.

http://www.math.com/tables/geometry/volumes.htm
http://www.online-calculators.co.uk/volumetric/cylindervolume.php
http://www.math10.com/en/geometry/volume.html

QUESTIONS YOU MAY WANT TO SOLVE IN YOUR FREE TIME:
What is the formula to find the volume of a Rectangular Prism?

length=3m, width=4m, height=5. What is the volume of this Rectangular Prism?

### Volume Post

Blue for first part of the question and answer
Green for second part of the question and answer
Question 15:
a) If the edge length of a cube is doubled, find the ratio of the old surface area to the new surface area.
b) What happens if the edge length of a cube is tripled? Is there a pattern?

a) 1:4. Instead of thinking of it as a cube, I thought of it as a square. Let's say a side of a cube's side lengths were 6m and had an area of 36cm2. You multiply the side lengths by 2, which becomes 12, and find the new area which is 144. 144/36=4. So, the ratio is 1:4.

b) If the side length is tripled, the new ratio becomes 1:9. There is a pattern if you continue doing this. All of the lengths are prime numbers while the other numbers stay the same. For example, 1:4, 1:9, 1:16, 1:25. ( x 4=64)

Question 16:

Shelby wants to paint the walls and ceiling of a rectangular room. 1 liter of paint covers 9.5 m2.

a) What is the least amount of paint Shelby can buy to paint the room (subtract 5 m2
for the door and windows)?
b) How much will the paint cost, including the amount of tax charged in your region?

The height is 2.6m2, the length is 4.8m2, the width is 6.8m2. 1 liter of paint covers 9.5 m2.

a) L x W
2.6 x 4.8
2.6 x 4.8
2.6 x 6.8
2.6 x 6.8
6.8 x 4.8
6.8 x 4.8=
125.6 125.6-5= 120.6
120.6-65.28 (the ceiling paint has to be separated from the wall paint)= 55.32
55.32/9.5=5.8

Wall paint: 1 can 4L, 2 cans 1L.
Ceiling paint: 1 can 4L.

b) The cost will be 82.75 with 12% GST and PST.
Wall paint: 4L= \$24.95
1L=\$7.99
Ceiling paint: 4L=\$32.95

24.95+7.99+7.99+32.95=73.88
12%= 8.87.
73.88+8.87= 87.75

Cylinder Volume and Volume Problems

7.3

Jumbo:

r=d÷2 V=pi.r.r.h
r=20÷2 V=(3.14x10x10)x40
r=10cm V=12,560cm³

Popcorn Lover's:

r=d÷2 V=pi.r.r.h
r=30÷2 V=(3.14x15x15)x20
r=15cm V=14,130cm³

Martha should buy the popcorn lover's one because it has more volume than the jumbo one.Popcorn Lover's volume is 14,130cm³ while Jumbo's 12,560cm³

7.4

Inside Circle:

r=d÷2 V=pi.r.r.h
r=8÷2 V=(3.14x4x4)x40
r=4cm V=2009.6cm³

Outside Circle:

r=d÷2 V=pi.r.r.h
r=10÷2 V=(3.14x5x5)x40
r=5cm V=3140cm³
3140cm³-2009.6cm³=1130.4cm³

I cant make a video yet, my camera is broken and being repaired, I will have to use some body else's tomorrow.

### Page 180-181 Questions 3,5,7,11

Questions 3

For #3 I did 2 ways. First I did a net to make my solving easier. For the 1st way I did is multiply lxw to all sides (top,front,side). Then I added all of the answer to get my Total Surface Area or T.S.A. For the 2nd way what I did is I drawed the lateral area then I added the lengths of it example 18.5. After I added it I then multiply it 13.5 because they all share 13.5. Then I multiply the side. Lastly, I added it all to get the T.S.A what I got is 819.5cm²

Question 5

For #5 I did is I first got the 3 rectangles surface areas. Then I did the triangle's surface area. After that I added all of it to get the T.S.A. (there's a diagram but it got cut off)

Question 7
What is the total surface area?

For #7 Basically it gave us the surface area of all sides. So you only to multiply each of them to 2 because for example if there's a top there's a bottom. After you multiply each of those add it to get the total surface area.

Question 11

For #11 I did is because he won't be painting the bottom square it has 4 faces. I did the l x w thing to each of the cubes and then I added it to get the T.S.A or total surface area.