CREATE TABLE lives_in (stuid VARCHAR, dormid VARCHAR)
CREATE TABLE student (age INT, stuid VARCHAR)
CREATE TABLE dorm (student_capacity INT)

Find the average age of students who are living in the dorm with the largest capacity.
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)
SELECT AVG("T1"."age") FROM "student" AS "T1" JOIN "lives_in" AS "T2" ON "T1"."stuid" = "T2"."stuid" JOIN "dorm" AS "T3" ON "T2"."dormid" = "T3"."dormid" AND "T3"."student_capacity" = (SELECT MAX("student_capacity") FROM "dorm")