dorm id , please.
select dormid from dorm order by student_capacity desc limit 1
How many students live there?
select count ( t1.stuid ) from lives_in as t1 join dorm as t2 on t1.dormid = t2.dormid where t2.student_capacity = ( select max ( student_capacity ) from dorm )
What is their average age?
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 )