How do we decide if 中 is ちゅう or じゅう?


How do we decide if 中 is ちゅう or じゅう ?

For example, in this sentence １０人中３人はビデオを持っている which pronunciation should we
use?

What about this: そのピアニストの演奏中、彼らは一心に耳を傾けた。




  * **じゅう** (or, rarely: ぢゅう) is used for expressions covering a **length** of time (resp. area) from start to finish, in its entirety. I.e. "through", "all of":

> 一年中【いちねんじゅう】 all year
>
> 一日中【いちにちじゅう】 all day
>
> 世界中【せかいじゅう】 all over the world

  * **ちゅう** is for pointing a particular time (resp. specific location) out of an interval (resp. general area). I.e. "out of", "during":

> 午前中【ごぜんちゅう】 [at some point] during morning
>
> 会議中【かいぎちゅう】 in a meeting [e.g. "he is in a meeting _at the moment_ "]

Note that in some cases, both can be used and the only way to tell would be
from context (e.g. an expression followed by に is more likely to be ちゅう) or in
speech:

> 来月中【らいげつじゅう】 all of next month
>
> 来月中【らいげつちゅう】 [some time] next month




  * **じゅう** (or, rarely: ぢゅう) is used for expressions covering a **length** of time (resp. area) from start to finish, in its entirety. I.e. "through", "all of":

> 一年中【いちねんじゅう】 all year
>
> 一日中【いちにちじゅう】 all day
>
> 世界中【せかいじゅう】 all over the world

  * **ちゅう** is for pointing a particular time (resp. specific location) out of an interval (resp. general area). I.e. "out of", "during":

> 午前中【ごぜんちゅう】 [at some point] during morning
>
> 会議中【かいぎちゅう】 in a meeting [e.g. "he is in a meeting _at the moment_ "]

Note that in some cases, both can be used and the only way to tell would be
from context (e.g. an expression followed by に is more likely to be ちゅう) or in
speech:

> 来月中【らいげつじゅう】 all of next month
>
> 来月中【らいげつちゅう】 [some time] next month

