## Wednesday, January 26, 2011

### 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.

1. GOOD JOB CAMERON! I liked how you added variety of colours and added a picture. Also, you added the Flisti survey. However, you could've added a video or a link for people to understand how the Total Surface Area works. But overall, you did a great job. Keep it up!:)

2. Good job Cameron!! I liked how you added color sand a picture. You even added a Flisti! Like Kathryn said, you might have wanted to add a video or some links. Keep up the good work!

3. G'JOB CAM (: I liked how you used colors and your work. Love the flisti ;) Next time you should add videos and links (: Keep up the good work!

4. GOOD JOB CAMERON! I liked the way you included a picture and explanation of your work. Also, you added Flisti but next time, try to make it more connected to math. Also, try to use colors just for important details. It sort of distracts me.
Anyways, keep up the good work!

5. Good job. I liked how you colour coated your work, it made it easier to read and understand. But next time you should add more pictures and try to keep the surveys about math.

6. Good Job Cameron! I liked how you added pictures and color on your scribe. Next time istead of adding the link of the youtube video you shouldd've have put the mebed into the html code or something and so we can watch it right on the scribe. Anyways Keep up the Goodwork!

7. Excellent JOb Cameron! I liked the way that you added in pictures, colors and polls unto your scribe, but next time try to organize your photo placing so that your sentences will not be squished, Other than that Good Job!

8. Good job Cam! I really like the picture and how you explained what you did through out the scribe. but next time try to add a link and a video to your post, keep up the good work.

9. Great Job Cameron! I like how your scribe is organized, great job on adding a picture and some explanation to help us more, you also added in Flisti. Next time try to add a link and a video to help us understand it more.

10. Good job, Cameron! I liked how you added pictures,a Flisti and colour. Though, next time only colour in the important words and make your poll related to math. Keep it up!

11. GOOD JOB CAMMY! I liked how you added pictures, a link to a video, and flisti questions. Although, next time, try to put less colours and only on the important words. Keep it up! (:

12. Good job Cameron. I liked how you used colour for the words. But next time only use colour for important words, not all of them.

13. Good job Cameron! I like how you have pictures, and color. Next time, try not to add color for all the words, but keep it up!