You are Here: Home >< Maths

# C4 HELP Watch

1. Can someone help me with q2b

https://a086a5a2f39bda93734c56a63fab...%20Edexcel.pdf

basically, i dont understand why they cubed the 4.

ms:
https://a086a5a2f39bda93734c56a63fab...%20Edexcel.pdf

thanks
2. Because there is a volume scale factor. The original to the object has a scale factor of 4 and so areas would go up by 16 and volumes by 64
3. (Original post by nerak99)
Because there is a volume scale factor. The original to the object has a scale factor of 4 and so areas would go up by 16 and volumes by 64
how comes it goes to 64? is there a rule or something
4. If you scale a thing by a ration a:b then areas go up by a scale of a^2:b^2 and volumes by a^3:b^3

So, for example if I scale a 1,1,1 cube by a ration 1:3. The side length goes from 1,1,1 to 3,3,3. Each face area from 1x1=1 to 3x3=9 (i.e 3^2) so 6 faces go from 6x1 to 6x9=54 which is still a area ratio of 1:9 and the volume from 1x1x1=1 to 3x3x3=27 (i.e 3^3).

Is that clearer?
5. (Original post by Lilly1234567890)
how comes it goes to 64? is there a rule or something
you square the length scale factor to get the area scale factor

you cube the length scale factor to get the volume scale factor
6. (Original post by the bear)
you square the length scale factor to get the area scale factor

you cube the length scale factor to get the volume scale factor
(Original post by the bear)
you square the length scale factor to get the area scale factor

you cube the length scale factor to get the volume scale factor
(Original post by nerak99)
If you scale a thing by a ration a:b then areas go up by a scale of a^2:b^2 and volumes by a^3:b^3

So, for example if I scale a 1,1,1 cube by a ration 1:3. The side length goes from 1,1,1 to 3,3,3. Each face area from 1x1=1 to 3x3=9 (i.e 3^2) so 6 faces go from 6x1 to 6x9=54 which is still a area ratio of 1:9 and the volume from 1x1x1=1 to 3x3x3=27 (i.e 3^3).

Is that clearer?
thanks !
7. (Original post by Lilly1234567890)
thanks !
no worries... don't be afraid to ask us stuff

TSR Support Team

We have a brilliant team of more than 60 Support Team members looking after discussions on The Student Room, helping to make it a fun, safe and useful place to hang out.

This forum is supported by:
Updated: June 18, 2016
Today on TSR

### Last-minute PS help

100s of personal statements examples here

### Loneliness at uni

Discussions on TSR

• Latest
• ## See more of what you like on The Student Room

You can personalise what you see on TSR. Tell us a little about yourself to get started.

• Poll
Useful resources

### Maths Forum posting guidelines

Not sure where to post? Read the updated guidelines here

### How to use LaTex

Writing equations the easy way

### Study habits of A* students

Top tips from students who have already aced their exams

## Groups associated with this forum:

View associated groups
Discussions on TSR

• Latest
• ## See more of what you like on The Student Room

You can personalise what you see on TSR. Tell us a little about yourself to get started.

• The Student Room, Get Revising and Marked by Teachers are trading names of The Student Room Group Ltd.

Register Number: 04666380 (England and Wales), VAT No. 806 8067 22 Registered Office: International House, Queens Road, Brighton, BN1 3XE

Reputation gems: You get these gems as you gain rep from other members for making good contributions and giving helpful advice.