Number of years in takes for real GDP in Brazil to double if the 2006 economic growth rate are maintained?

Question

Brazil's real GDP was 1,082 billion reals in 2005 and 1,120 billion reals in 2006. Brazil's population growth rate in 2006 was 1.2 percent. The approximate number of years it takes for real GDP per person in Brazil to double if the 2006 economic growth rate and poplulation growth rate are maintained is ___ years.

How would I solve this?

Answer 1

[(1120/1.012)/1082]^n=1.022846^n =2
so log(2)/ log(1.022846) =n =30.7 where n is number of years