Mathematics Stack Exchange
Mathematics Stack Exchange

Questions tagged [ratio]

For questions concerning the ratio of a certain quantity to another.

In mathematics, a ratio is a relationship between two quantities indicating how many times the first number contains the second. For example, if a bowl of fruit contains eight oranges and six lemons, then the ratio of oranges to lemons is eight to six (that is, $8:6$, which is equivalent to the ratio $4:3$). The numbers compared in a ratio can be any quantities of a comparable kind, such as objects, persons, lengths, or spoonfuls. A ratio is written "$a$ to $b$" or $a:b$, or sometimes expressed arithmetically as a quotient of the two.

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A scaling factor for a logo that decreases as page gets bigger

I'm Okay with fixed scaling factors but this has got me beat. I have a page that is 100mm and a logo that is 25mm wide making it 25% of the page width when the logo is scaled at 100%. As the page size increases I want to enlarge the Logo also - but…
Toggs
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How to bridge operational efficiency ratio between two periods?

I am looking at operational efficiency as a ratio of indirect production costs to gross profit 1 (GP 1 does not include these indirect costs) (Ind Prod/GP). I have been asked to bridge the difference in the ratio between two periods. Let us assume…
Niclas
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Express density as a ratio of height

D1 and D2 are densities $$D1 = \frac{3*mass}{4*pi*r^3} $$ $$D2 = \frac{3*mass}{pi(3rh^2-h^3)} $$ and then $$\frac{D2}{D1} = \frac{3rh^2-h^3}{4r^3}$$ I'm not sure how to isolate the R and H so when given the two densities I can just calculate the…
Jake Stan
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How to convert ratios

I have a camera that returns an image with a 4:3 aspect ratio, while the dimensions of its preview are 16:9. What math would I need to apply to crop the 4:3 photo to 16:9 ?
maddie
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How do I determine how much does a variable "vary" by looking at other variables it depends on?

I'm aware this is pretty basic, I'm having trouble with directly and inversely proportional variations. I have this equation $$ A = \frac{BC^2\sqrt{D}}{E.F^3} $$ So, as I understand it, if $B$ gets bigger, $A$ should also get bigger as they are…
undefined
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Problem with Ratios

I was doing some problems out a book I had at home and found this problem: If $15(2x^2-y^2) = 7xy$, find the ratio of $x : y$ Maybe I've been staring at it for too long (or maybe I'm not thinking correctly), but how would I quickly solve this…
ssharma
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How can I figure out what the scale of an object is going to be?

I've been stuck on this question for weeks can anyone please explain this to me? Cate drew an animal that she wants to create. She said that it would obviously be bigger than the drawing because she used a scale of $1cm:13 inches$. Based upon…
April Weaver
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What is the function to get the width/length of a house if I need a given ratio ($1:1.6$) and the outer wall has a thickness?

We are dreaming building a house with a net (netto) area of $100m^2$. Net means the thickness of the outer walls are not counted regarding the area. Inner walls doesn't matter now. The ratio needs to be $1 : 1.6$ regarding the outer sides. The…
Peter
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How to calculate inverted ratios? The one with most gets the least kinda thing?

Assume that in this question, $A = 20, B = 30, C = 50$. They find $\$100$ and want to split by ratios such that the one with the least amount at the moment gets the most. $A$ will get the most, $B$ after that, and $C$ the least and this division…
E. Afzal
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Is there a way to find the closest ratio to another ratio but in different sum?

Firstly, let me apologize for my unclear title. I don't know how to describe this. Here is more description. Given a ratio $$x = x_1 : x_2 : x_3 : \cdots : x_n$$ where $s = \sum x_i$ and $x_i, n \in \mathbb{Z}^+$ Given $t$, is there any way to…
Jason Yu
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Finding ratio of length of radii from ratio of areas?

The Question: A central angle of two concentric circles is $\frac{3\pi}{14}$. The area of the large sector is twice the area of the small sector. What is the ratio of the lengths of the radii of the two circles? Answer: 0.71:1 The answer I end up…
ak_27
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if £10 becomes £25, has it been increased or decreased, and in what ratio?

I'm currently working on simple ratios for GCSE and I am comfortable calculating shares via ratios and increasing/decreasing a value by a ratio. However, I dont understand how to calculate the ratio when it comes to questions as per the title. Could…
iNoob
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Difficulty in proving a result

If $\frac{ay-bx}{c}$ = $\frac{cx-az}{b}$ = $\frac{bz-cy}{a}$ , prove $\frac{x}{a}$= $\frac{y}{b}$ = $\frac{z}{c}$. My attempt: $\frac{(ay-bx)z}{cz}$ = $\frac{(cx-az)y}{by}$ = $\frac{(bz-cy)x}{ax}$ ⇒$\frac{ayz-bxz}{cz}$ = $\frac{cxy-ayz}{by}$ =…
MrAP
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Finding wages of each worker

A, B and C undertake to do a piece of work for Rs.1950. A work for 8 days, B for 9 days and C for 12 days to complete the work. If their daily wages are in the ratio of 3:5:4 , What does C get ?
user212937
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How to avoid mixing up ratios when comparing two values?

In the following question for example: $1$ Neptune day = $18$ hours. $1$ Earth day = $24$ hours. How many Neptune days = $10$ Earth days? My intial reaction was to do the following: $$\frac{18..Hours (on.Neptune)} {24..Hours…
K-Feldspar
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