How many distinct hometowns are there?
select count(distinct hometown) from people
How many gymnasts are there in each hometown?
select t2.hometown, count(*) from gymnast as t1 join people as t2 on t1.gymnast_id = t2.people_id group by t2.hometown
Which hometown has more than 1 gymnast?
select t2.hometown from gymnast as t1 join people as t2 on t1.gymnast_id = t2.people_id group by t2.hometown having count(*) >= 2