list the names of all male dorms (with gender M).
select dorm_name from dorm where gender = 'M'
how many are there?
select count(*) from dorm where gender = 'M'
Find the total number of students living in these dorms.
select count(*) 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.gender = 'M'