Write SQL query to solve given problem: How many female students were there at Stanford University in 2011?. Keep the solution inside sql tag ```sql [SQL-Query] ```
SELECT CAST(T1.num_students * T1.pct_female_students AS REAL) / 100 FROM university_year AS T1 INNER JOIN university AS T2 ON T1.university_id = T2.id WHERE T1.year = 2011 AND T2.university_name = 'Stanford University'