Table: district_population_2011
Columns: administrative_division
area_km_2011
population_2001_census_adjusted
population_2011_census_adjusted
population_density_km_2011

Question: What was the population density in km2 for 2011 in the division where area in km2 was 684.37 in 2011? 
SQL: SELECT "population_density_km_2011" FROM district_population_2011 WHERE "area_km_2011" = '684.37'

Question: What division had a population density of 8,552.4 km2 in 2011?
SQL: SELECT "administrative_division" FROM district_population_2011 WHERE "population_density_km_2011" = '8,552.4'

Question: What was the area in km2 in 2011 for the Narsingdi District?
SQL: SELECT "area_km_2011" FROM district_population_2011 WHERE "administrative_division" = 'Narsingdi District'

Question: In what division was there a population density in km2 of 1,604.3 in 2011?
SQL: SELECT "administrative_division" FROM district_population_2011 WHERE "population_density_km_2011" = '1,604.3'

Question: In what division was there a population density in km2 of 4,491.8 in 2011? 
SQL: SELECT "administrative_division" FROM district_population_2011 WHERE "population_density_km_2011" = '4,491.8'