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Ratio: How much of one thing compared to the other.

But we have got two different types of definitions of Proportions:

  1. How much of one thing is compared to the total.

  2. Proportion says two ratios are equal.

And sometimes I see people using the words ratio and proportion alternatively.

As I am a basic mathematics learner I am totally confused.

Please help me understand the two concepts.

Thanks in advance.

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user100323
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  • A proportion is an equation that sets two ratios equal to each other. A ratio is simply a fraction of two quantities. Does that make sense? – Rushabh Mehta Nov 03 '19 at 03:01
  • You are overthinking. a/b=c/d means that a to b has the same ratio as c to d. The word proportion is synonymous in this context. Also f/g=h means the ratio of f to g is h. – herb steinberg Nov 03 '19 at 03:03
  • @herbsteinberg do you mean that ratio itself becomes a proportion if we take into consideration things on the both side of the equal sign? – user100323 Nov 03 '19 at 03:08

1 Answers1

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  1. The ratio of any number of quantities is a quantitative comparison of their measures.

    In particular, the binary ratio $T:H$ is equivalent to the fraction $\displaystyle\frac TH.$

  2. On the other hand, direct proportion equates ratios of corresponding values.

    For example, variables $T$ and $H$ being in (direct) proportion means that as they vary, $$\frac {T_i}{H_i}\equiv \frac {T_1}{H_1}=\frac {T_2}{H_2}=\frac {T_3}{H_3};$$ in other words, the pairs of corresponding values $(T_i,H_i)$ are in (direct) proportion.

  3. Variables $T$ and $H$ being in inverse proportion means that as they vary, $$T_iH_i\equiv T_1H_1=T_2H_2=T_3H_3.$$

  4. In less technical contexts, a “proportion” of a quantity is a proper fraction or percentage smaller than $100\%.$

ryang
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