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CREATE TABLE Classrooms (CourseId int, StudentId int); CREATE TABLE Students (StudentId int, Gender char); SELECT c.CourseId, COUNT(DISTINCT CASE WHEN s.Gender = 'F' THEN c.StudentId ELSE NULL END) AS Women, COUNT(DISTINCT CASE WHEN s.Gender = 'M' THEN c.StudentId ELSE NULL END) AS Man, COUNT(DISTINCT CASE WHEN s.Gender = 'M' THEN c.StudentId ELSE NULL END) / COUNT(DISTINCT CASE WHEN s.Gender = 'F' THEN c.StudentId ELSE NULL END) AS Rate FROM Classrooms c INNER JOIN Students s ON c.StudentId = s.StudentId GROUP BY c.CourseId HAVING COUNT(DISTINCT CASE WHEN s.Gender = 'M' THEN c.StudentId ELSE NULL END) / COUNT(DISTINCT CASE WHEN s.Gender = 'F' THEN c.StudentId ELSE NULL END) > 0.5