Geometry scale factor

[rachelmaddie]

How do you convert scale factor to a ratio?
We want to go from "a = 18*b" to "the ratio of a to b is x/y (or x:y)". What's x/y?

If you look at my work from above. I don’t know if that’s correct

 

[lev888]

If you look at my work from above. I don’t know if that’s correct

You don't know how to get 18:1 or you don't know whether this is the representation of a ratio your teacher expects?

 

[rachelmaddie]

You don't know how to get 18:1 or you don't know whether this is the representation of a ratio your teacher expects?

I don’t know if this is correct from post #7

Convert the banner from feet to inches for both sides to be measured in the same units.
12 inches = 1 foot
15 x 12 = 180
ratio = one side of the photo/one side of the banner
180/10
By dividing both sides by 10
180/10 = 18/1
The scale factor is 18:1

 

[lev888]

I don’t know if this is correct from post #7

Convert the banner from feet to inches for both sides to be measured in the same units.
12 inches = 1 foot
15 x 12 = 180
ratio = one side of the photo/one side of the banner
180/10
By dividing both sides by 10
180/10 = 18/1
The scale factor is 18:1

I already replied in #17 that it looked good to me. What are the remaining issues? Whether the answer should be 18 and 18:1? That's up to your teacher, I have no idea.

 

[rachelmaddie]

I already replied in #17 that it looked good to me. What are the remaining issues? Whether the answer should be 18 and 18:1? That's up to your teacher, I have no idea.

Yes it is suppose to be expressed as a ratio.

 

[rachelmaddie]

Yes it is suppose to be expressed as a ratio.

I didn’t know that before posting my other thread for scale factor. Could you help me with that as well?

 

[lev888]

I am sorry, but I don't understand what you need.

 

[rachelmaddie]

I am sorry, but I don't understand what you need.

I’ve posted my work in the other thread for scale factor. I want to make ive done it correctly.

 

[lev888]

I’ve posted my work in the other thread for scale factor. I want to make ive done it correctly.

Ok, so you know that if the scale factor is 18 then the ratio is 18:1. In the other thread the scale factor is 5. Are you _really_ not sure whether the ratio is 5:1?

 

[rachelmaddie]

Ok, so you know that if the scale factor is 18 then the ratio is 18:1. In the other thread the scale factor is 5. Are you _really_ not sure whether the ratio is 5:1?

No I’m not.

 

[lev888]

No I’m not.

How do we get 18:1 from 18?

 

[rachelmaddie]

No I’m not.

By dividing by 10?

 

[lev888]

By dividing by 10?

Scale factor C means a = C*b.
Ratio of a to b is a/b. If a = C*b we can use C*b instead of a: a/b = (C*b)/b = C. Or C/1. Or C:1.

 

[rachelmaddie]

Does this work?

If you're scaling up from a smaller figure to a larger one, plug the lengths into the equation scale factor = larger length over smaller length
By dividing both sides by 11
55/11 = 5/1
By dividing both sides by 9
45/9 = 5/1
Scale factor = 5:1

 

[Steven G]

In my opinion a scale factor is just a number. So I would say that the scale factor is 18.

However you claim that a scale factor is a ratio. To me a fraction is a ratio. So I would write 18 as 18/1 as my answer. If that type of representation is not correct for you class (wasn't it you who said that you are self studying?) or for you textbook then the only other answer is to go from 18 to 18/1 and then to 18:1

This question is painfully hard to answer as I do not know the exact form you want the answer in. In any case I gave the answer in three different forms. If none of them is what you want then just give us the exact form of any ratio from your book and we will tell you how to convert 18 into that form. Please get my point that you 1st need to get to 18 and then convert to another form.

 

[Deleted member 4993]

Does this work?

If you're scaling up from a smaller figure to a larger one, plug the lengths into the equation scale factor = larger length over smaller length
By dividing both sides by 11
55/11 = 5/1
By dividing both sides by 9
45/9 = 5/1
Scale factor = 5:1

Either one is acceptable to me.

It is between you and your instructor to decide which one is acceptable for your particular course!