Question 3986
start with a=10,000
after 1 year, got 1.12a --> 
after 2 years, got {{{1.12^2a}}} -->
after 3 years, got {{{1.12^3a}}} -->

after n years, got {{{(1.12^n)a}}} --> 30,000


so, {{{1.12^n}}} = 3
nlog(1.12) = log3
n = log3/log(1.12)


n = 9.69


so, it takes 10 years.



jon