Show me the names of all the perpetrators with a height of more than 1.84 meters.
select t1.name from people as t1 join perpetrator as t2 on t1.people_id = t2.people_id where t1.height > 1.84;
What's their average number of killed people?
select avg(t2.killed) from people as t1 join perpetrator as t2 on t1.people_id = t2.people_id where t1.height > 1.84;
How about the total?
select sum(t2.killed) from people as t1 join perpetrator as t2 on t1.people_id = t2.people_id where t1.height > 1.84;