**Question 18**

Suki has

**30**small linking cubes.

a) She wants to use

**18**of them to make a

**large cube**. Is this

**possible**?

**Why**or

**why**not?

b) What

**number**of linking cubes would she use to

**construct**the

**largest cube**she can

**possibly make**?

**Answers:**

a) Suki

**can not**make a large cube using 18 small linking cubes because

**18 is not a cubed number**.

**Work:**

1 x 1 x 1= 1³ Under 18 cubes

2 x 2 x 2= 8³ Under 18 cubes

3 x 3 x 3= 27³ Over 18 cubes

b) Suki needs

**27 linkings cubes**in order to make a

**3 by 3 cubes**in order to make the largest cube with a maximum amount of 30 small linking cubes.

**Work:**

1 x 1 x 1= 1³

2 x 2 x 2= 8³

3 x 3 x 3= 27³ Maximum amount for constructing a cube using under 30 linking cubes

4 x 4 x 4= 32³ Over 30 small linking cubes

19. Melissa has

**three glass vases**. She wants to use

**one**as a decorative fish tank for Harvey the guppy. Which will give Harvey the

**most water**to swim in?

**Volume of Cube:**

Side x Side x Side= Area of cube

7 cm x 7 cm x 7 cm = 343 cm³

**Volume of Rectangular Prism:**

Area of Base x Height= Area of Rectangular Prism

Length x Width= Area of Base

10 cm x 9 cm= 90 cm²

Height= 4 cm

90 cm x 4 cm= 360 cm³

Volume of Rectangular= 360 cm³

Volume of Triangular Prism:

Volume of Triangular Prism:

(Base x Height) / 2 x Height= Volume of Triangular Prism

(7 cm x 5 cm) / 2 x 21 cm=

35 cm / 2 x 21 cm=

17.5 cm x 21 cm= 367.5 cm³

Volume of Triangular Prism= 367.5 cm³

**Harvey will have the most water to swim is in the triangular prism**.

**Here is a link to educate you if you are still unsure about cubing or volume. Also here is a volume calculator to help you with volume work.**

**Video About The Volume Of A Rectangular Prism**

**Video About The Volume Of A Cube**

**Video About The Volume Of ATriangular Prism**

**Problem From Chapter 7.3**

**Work:**

Formula: (π x r x r) x h= v

(3.14 x 12cm x 12cm) x 15cm= v

452.16cm² x 15cm=6782.4cm³

6782.4cm³ / 4= 1695.6cm³

Volume= **1695.6cm³**

**Problem From Chapter 7.4**

The capacity of the pipe, to the nearest tenth of a cubic centimetre is

**1130.4cm³**.

**Work:**

**Outer Volume:**

d/2= r

10cm/2= 5cm

(** **π x r x r) x h= v

(3.14 x 5cm x 5cm) x 40cm= v

78.5cm² x 40cm= 3140cm³

Volume of Outer Pipe= **3140cm³**

**Inner Volume:**

d/2= r

8cm/2= 4cm

(π x r x r) x h= v

(3.14 x 4cm x 4cm) x 40cm= v

50.24cm² x 40cm= 2009.6cm³

Volume of Inner Pipe= 2009.6cm³**Subtraction of Both Pipes:**

Formula outer pipe - inner pipe= capacity of pipe

3140cm³ - 2009.6cm³= 1130.4cm³

Capacity of Pipe= **1130.4cm³**

**EXTRA**

**Here is a link of a volume of a cylinder calculator.**

**Video About Finding The Volume Of A Cylinder**

**My Cylinder Video**

I am extremely sorry if my voice sounded weird and that it sounded disorganized because I got a cold and I didn't have a script or practice. In other words to be honest I just made up the whole thing in my head while recording this video. Also if there are any problems feel free to comment or suggest below in the comment box. I will try to accommodate you to the best of my ability. In addition I might have made some spelling errors during, but I have fixed them after discovering them. Good luck on our upcoming test on March 2,2011!

I am extremely sorry if my voice sounded weird and that it sounded disorganized because I got a cold and I didn't have a script or practice. In other words to be honest I just made up the whole thing in my head while recording this video. Also if there are any problems feel free to comment or suggest below in the comment box. I will try to accommodate you to the best of my ability. In addition I might have made some spelling errors during, but I have fixed them after discovering them. Good luck on our upcoming test on March 2,2011!

Great Post Duyen. Your post was very neat and easy to understand. Your answers were very detailed. I also noticed you didn't know how to do a cubed ans squared sign. For squared it's (alt+253) ².

ReplyDeleteFor cubed it's (alt+0179) ³. The videos and link also helped, Great Job.

Thank you, Paul! I will fix that on my scribe post and any other future scribe posts.

ReplyDeleteGreat job Duyen. Your post was very neat and had a lot of colors which made it stand out. I liked that you colored the important things. Keep up the great work.

ReplyDelete