Table: nauru_districts
Columns: nr
district
former_name
area_ha
population_2005
no_of_villages
density_persons_ha

Question: If there are 18 villages, what is the minimum area ?
SQL: SELECT MIN("area_ha") FROM nauru_districts WHERE "no_of_villages" = 18

Question: With the population in 2005 of 572, what is the former name?
SQL: SELECT "former_name" FROM nauru_districts WHERE "population_2005" = 572

Question: How many villages have a density persons/ha of 5.5?
SQL: SELECT COUNT("no_of_villages") FROM nauru_districts WHERE "density_persons_ha" = '5.5'