Question

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So, I know I have to setup proportions, but could someone explain why there's a specific way you set them up? For eg, I set mine up 47/x=82.8/92 but I get the wrong answer. But when it's setup as 47/x=82/73.8 it gives you the right answer. So, I tried to setup as 47/x=92/73.8 it gives the wrong answer. I'm really confused why. The only reply I've gotten so far is "there is a correct way to setup proportions", but I don't understand what the correct way is.

Answer 1

@Directrix
I've looked into this for awhile, but I'm still having issues understanding what a proportion is. No matter how different sites explain it, the wording confuses me. Could you explain proportions and ratios to me in very simple terms and then tell me the correct way to setup a proportion so I understand this question?

Answer 2

It would be better, I think, to talk about a specific problem.

A proportion is two equal fractions.

But, how the set-up is done appears on the details of the particular problem and what any theorem being used states.

What problem gave you this: 47/x=92/73.8

Answer 3

What problem? Did the screenshot not pop up? Or are you asking me the theorem?

Answer 4

Also, if a proportion is two equal fractions when they say triangles are proportional they mean the sides are equal?

Answer 5

No, they mean the corresponding sides are in proportion.

Answer 6

>>when they say triangles are proportional they mean the sides are equal?

No.

If two triangles are similar, then the lengths of corresponding sides are in proportion.

Answer 7

What's the difference between in proportion and proportional?

Answer 8

You said this --> I tried to setup as 47/x=92/73.8 it gives the wrong answer.

I asked you to post the problem that gave you the wrong proportion so that we could use that problem as a vehicle to get at your confusion about proportions.

Answer 9

Ah, skull patrol posted it. : )
You see it right?

Answer 10

A proportion is an equation stating that two ratios are equal.
$$\dfrac{a}{b}=\dfrac{c}{d}$$

Answer 11

a is to b as c is to d

Answer 12

So, in proportion I assume means congruent then?

And proportion means two ratios are equal? A ratio is just two numbers right?

Answer 13

The ratio of two numbers is their quotient.

Answer 14

>You see it right?

Yes.

I also see that there is no statement that the two triangles are similar.

And, there is no similarity statement of the corresponding vertices of the two triangles.

That very likely is causing your errors.

To say, in general, that Triangle ABC ~Triangle DEF is not the same as stating that Triangle BAC ~ Triangle DEF.

The corresponding sides would be different and would result in a different proportion.

Answer 15

Hm, that sounds weird.

A ratio is a quotient? So a proportion is the result of division?

Direct, would you like me to post the theorems I'm using as well so you know what I'm doing in case those are incorrect?

Answer 16

A ratio is the result of division.

A proportion is an equation that states that two results of division are equal.

Answer 17

So for eg 3 divided by 9 is 3:9 and a proportion is 3/9=1/3

Answer 18

lol were the only 1 online

Answer 19

yes

Answer 20

Oh wow alright I think I get it now. So would it be fair to say a ratio is a division setup technically?

Answer 21

yep

Answer 22

yes

Answer 23

12 is not a ratio but 12/1 is a ratio

Answer 24

I get it now.
Wait, what would be the proportion to that?

Answer 25

24/2 = 12/1

Answer 26

24 is to 2 as 12 is to 1

Answer 27

i see what you did there.

So is that the reason why in a ratio a/b is only a proportion when b isn't 0 because the result of the division problem would be 0 therefore not needing a proportion?

Answer 28

can i get medal if i help

Answer 29

Haha, sure. I'm actually just making sure I understand proportions and ratios before I move on to the actual problem I posed. Though, I'm probably going to give it to skull if I'm being honest. So, I would help someone else.

Answer 30

yea he does deserve 1

Answer 31

the result of the division using 0 as a divisor is "undefined"

you can not compare any real number to 0 length, right?

Answer 32

i gave u a medal skull patrol

Answer 33

Thanks :D

Answer 34

yw

Answer 35

Oh that makes sense!
I'll give you a medal now but please don't leave me in the middle of my problem like some people do okay LOL.