Question: Find the average age of students who are living in the dorm with the largest capacity.
SQL: SELECT avg(T1.age) FROM student AS T1 JOIN lives_in AS T2 ON T1.stuid  =  T2.stuid JOIN dorm AS T3 ON T3.dormid  =  T2.dormid WHERE T3.student_capacity  =  (SELECT max(student_capacity) FROM dorm)