Translation of "fraction" in a sentence
Suppose 73% of the population is educated, and 4/7 of the educated is smart. Suppose further that 2/3 of the uneducated is smart as well. What is the probability that a randomly selected educated person is smart?
假设73%的人口受过教育，而受过教育的人当中4/7是聪明的。进一步假设2/3没受过教育的人也是聪明的。随机抽取一个受过教育的人是聪明的概率是多少？

&quot;(Ratio q) + of + X&quot; can be translated as

(在)X(当)中q. &quot;(在)受过教育的人(当)中4/7是聪明的&quot;. And &quot;其中4/7是聪明的&quot; sounds more concise – though IMO it can't be applied to this example because it's a little ambiguous.
qX. &quot;4/7受过教育的人是聪明的&quot;. Sometimes for the subtle fluency, when X doesn't contain &quot;的&quot;, it would be better to say  &quot;q的X&quot; instead, such as &quot;4/7的农民&quot;, &quot;30%的学生&quot;.
X的q. It sounds a little colloquial and a little awkward for this example because there're two close &quot;的&quot;s: &quot;受过教育的人的4/7是聪明的&quot;.

(Ratio q) above can be replaced by a percentage &quot;p%&quot; too. Either &quot;(在)受过教育的人(当)中50%是聪明的&quot; or
&quot;(在)受过教育的人(当)中p%是聪明的&quot; (p% as a variable) is fine.
However, if you have to use &quot;ratio q&quot; as a variable, it has to be &quot;比例q&quot; or &quot;比率q&quot;, and a &quot;有&quot; would be necessary: &quot;受过教育的人中有比率q是聪明的&quot;. Though maybe not everyone consider it clear enough - &quot;比率q的X&quot; and &quot;X的比率q&quot; patterns are even worse.
PS: I don't see the point of this math problem. If we just randomly select a person within the educated, i.e. P(smart|educated), then, isn't the answer a trivial 4/7? Have I missed anything? :/