Found a sentence,

> 人間の身体能力は吸血鬼の **7分の1** しかありません

Is this how you write ratios in Japanese?
CC BY-SA 3.0
2015-07-13T09:26:27.330
25657
2015-07-17T10:06:27.483
2015-07-16T15:24:34.887
10345
question
translation words mathematics
Does 「7分の1」 mean 1:7 in this sentence?
Yes.

> n / m = n : m

is written

> m分のn,

where "m" and "n" are positive integers.

BTW, is

> 人間の身体能力は、吸血鬼の身体能力の7分の1しかありません

more acceptable for you?

*** added ***

I just learned that the notation n : m confuses some people.

Here is what Hans Lundmark pointed out to me in regard of the usage of n : m.
I hope this helps to resolve their confusion.

> You have good historical reasons for interpreting n:m as n/m.
>
> From <http://jeff560.tripod.com/operation.html>:
>
> The colon (:) was used in 1633 in a text entitled Johnson Arithmetik; In two
> Bookes (2nd ed.: London, 1633). However Johnson only used the symbol to
> indicate fractions (for example three-fourths was written 3:4); he did not
> use the symbol for division "dissociated from the idea of a fraction"
> (Cajori vol. 1, page 276).
>
> Gottfried Wilhelm Leibniz (1646-1716) used : for both ratio and division in
> 1684 in the Acta eruditorum (Cajori vol. 1, page 295).

As for the said excerpt, it reads "The (average?) physical ability of
humankind is one-seventh of that of vampire."

*** added (again) ***

In view of the _established_ usage as described in
<http://www.bradford.ac.uk/wimba-files/msu-
course/media/ratio%20teaching%20new.pdf> , the assertion by @Earthliŋ

> n : m is usually the notation for "n parts in (n+m) parts vs. m parts in
> (n+m) parts", so 1:7 would correspond to 1/8 and 7/8

should read

> In the context that something is to be divided into n : m, it can be
> considered as "n parts in (n+m) parts vs. m parts in (n+m) parts", so 1:7
> can be specified as the pair (1/8, 7/8) if needed.
CC BY-SA 3.0
2015-07-13T09:47:43.540
25659
2015-07-17T10:06:27.483
2015-07-17T10:06:27.483
10402
10402
25657
answer
Not exactly (as several have commented). This is how you talk about
_fractions_ in Japanese:

> 7分の1 → 1/7

Literally, you can think about it as 'one part of seven'. It is not a ratio,
i.e. 'one part to seven parts', as that equates to 1/8.
CC BY-SA 3.0
2015-07-13T23:55:06.920
25670
2015-07-13T23:55:06.920
3639
25657
answer
Yes, 「７分の１」 means same as 1:7 mathematically.

1:7 = (1/8):(7/8) = (1/8)/(7/8) = (1/8)x(8/7) = 8/56 = 1/7

However, in Japan, kids are taught that 1:7 is 「[比]{ひ}」 and 1/7 is
「[分数]{ぶんすう}」. I guess that 「比」 is translated as "ratios", and 「分数」 is
translated as "fractions" generally. So, Japanese people tend to think that
1/7 is not a ratio, maybe.

In English, both 1:7 and 1/7 can be read "one to seven", right? And both 1:7
and 1/7 are called "ratio" in some cases, maybe? (Sorry, if my knowledge about
English is wrong.) But in Japanese, each of them has its own way to be read.

> 1:7 is read 「[１]{いち}[対]{たい}[７]{なな}」.

> 1/7 is read 「[７]{なな}[分]{ぶん}の[１]{いち}」.

There are other ways to express proportions in Japanese. For example,

> 1/10 is read 「[１]{いち}[割]{わり}」 ＝ 10%
>
> 2/10 is read 「[２]{に}[割]{わり}」 ＝ 20%

Which word should be used is up to the situation and context.

If your "ratio" means both 1:7 and 1/7, I would answer that there are several
ways to write ratio in Japanese, and 「７分の１」 is one of them. So, yes.
CC BY-SA 3.0
2015-07-14T07:10:49.167
25681
2015-07-14T07:10:49.167
2020-06-17T08:18:27.500
-1
10484
25657
answer