Table: province_population_2011
Columns: rank
province
population_2011
percentage
population_estimate_2013

Question: What is the rank of the gauteng province?
SQL: SELECT "rank" FROM province_population_2011 WHERE "province" = 'gauteng'

Question: What is the lowest 2013 population estimate of the province with a 23.7 percentage?
SQL: SELECT MIN("population_estimate_2013") FROM province_population_2011 WHERE "percentage" = 23.7