您将如何在Rails 4+中执行此查询

Question

我现在正在执行sql Zoo，并尝试学习查询，然后在Rails中进行处理-Active Record，我看不到让内部查询正常工作，也没有使人口/ 3查询正常工作。谢谢

 SELECT name, continent FROM world AS x
    WHERE population / 3 > ALL(SELECT population FROM world AS y
    WHERE x.continent = y.continent
    AND x.name != y.name)