You need to look at the per capita GDP and per capita GDP adjusted for purchasing power parity (PPP) to measure the relative economic strength of countries regardless of population disparities. Chile should have a smaller GDP; it has 16 million people compared with Brazil's 180. However, its GDP is proportionally higher:

http://en.wikipedia.org/wiki/List_of_countries_by_GDP_%28nom...

Chile: 48th; Brazil: 58th

http://en.wikipedia.org/wiki/List_of_countries_by_GDP_%28PPP...

Chile: 53rd; Brazil: 75th

(both taken from the World Bank list)