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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Understanding ratios in real world problems.

I'm studying maths as an adult, and I thought everything was going well until I hit the following activity. I have the answer in my workbook, but I just don't seem to be able to come to terms with the process. "8 pumps working for 10 minutes raise…
timstermatic
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"A project is normally finished in x days", but this time new workers are coming in after y days. What should I base my solution on?

I am copying the following example from a textbook. Example: A project can be completed by 150 workers in 40 days. But the project manager brought in 30 more workers after 16 days. In how many days will the remaining work be finished? Solution:…
Solace
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Eight inches of heavy, wet snow are equivalent to four inches of rain. Estimate the water content in 17 inches of heavy, wet snow.

Eight inches of heavy, wet snow are equivalent to four inches of rain. Estimate the water content in 17 inches of heavy, wet snow. Ok I get 8.4 as the answer for this problem but by calculator I get 8.5 and the answer that is right is 8.5. I'm not…
PostMagne
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How to Calculate gear ratio for potentiometer

I am not a mathematician so please bare this in mind. I am designing a computer steering wheel, using real car parts (fitting the steering wheel from a hatchback via gears to a potentiometer which is wired to a game controller). The steering column…
gcoulby
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Why does $\tfrac{a}{b} = \tfrac{c}{d} = \tfrac{e}{f} \rightarrow \tfrac{a}{b} = \tfrac{c-e}{d-f}$

Why is it that $$\frac{a}{b} = \frac{c}{d} = \frac{e}{f} \rightarrow \frac{a}{b} = \frac{c-e}{d-f}$$ It is used in the proof of Ceva's theorem. Thank you.
why
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Simplify ratio 152:121.6:212.8

How am I supposed to know that I can simplify the ratio by dividing with 30.4? Is that such an obvious common factor? How would you go about this if you had 60 seconds time to solve it? You're supposed to arrive at 5:4:7.
TMOTTM
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Dividing contents with ratios

I'm taking a mock test and there is a relatively straight forward question that I am not sure about. Sara and Jenny share some money in the ratio 6:7 Sara gets $96.00 How much does Jenny get? In order to do this question, do I do something like…
Jimmy
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Ratios to get the total

How do you solve this question? A cookie jar contains only two types of cookies - macaroons and ginger snaps. The ratio of macaroons to ginger snaps is $2:5$. Which of the following could be the total number of cookies in the cookie jar? [X]…
Alex
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Proportions question with ratios

Can you help me understand the answer to this question? At a Halloween party, there are 30 guests, 16 of whom are Draculas and 14 of whom are Mummies. Assuming no Mummies leave, how many Draculas need to arrive to make the ratio of Draculas to…
Alex
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Question regarding ratio

I was trying to prove some of the results related to beta function and I came across this step Therefore, $$\frac{B(m+1,n)}{m}=\frac{B(m,n+1)}{n}=k,\quad\mathrm{say}\quad\ldots(i)$$ This yields $$k=\frac{B(m+1,n)+B(m,n+1)}{m+n}$$ Can anyone…
GTX OC
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Calculate ratio $\frac{p^{3n}}{(\frac{p}{2})^{3n}}$

How do I calculate this ratio? I do not know even where to begin. $$\frac{p^{3n}}{(\frac{p}{2})^{3n}}$$ Thanks
S0rin
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relationship between proportions

consider some variables $x_1,x_2,y_1,y_2$ that are positive and for which $\frac{x_1}{y_1}=\frac{x_2}{y_2}=p$. Is it true that $\frac{x_1+x_2}{y_1+y_2}=p$?
user3761743
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Getting maximum values from a set of numbers in a ratio

I need to keep a set of five elements [a:b:c:d:e] in a ratio of [2:1:3:2:1]. I have a collection of [2035, 1050, 3060, 2040, 1027]. I need to take maximum amount of the elements according to ratio and keep the rest…
Amin
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How does the definition of ratios in book 5 of the Elements allow for dealing with the ratio of incommensurable numbers

Definition in Book 5 of the Elements "Magnitudes are said to be in the same ratio, the first to the second and the third to the fourth, when, if any equimultiples whatever are taken of the first and third, and any equimultiples whatever of the…
CatsOnAir
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Combining proportionality equations fails to solve "5 chickens can lay 10 eggs in 20 days" problem

5 chickens can lay 10 eggs in 20 days. How long does it take 18 chickens to lay 100 eggs? Let $c,g,d$ be the number of chickens, eggs, days, respectively. $c$ is inversely proportional to $d:\quad cd=x$ $g$ is directly proportional to $d:\quad…
Atul Anand
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