Question 133078
The formula for the population in any year would be
{{{f(x) = 100 (1.08)^n }}}

So to solve for a population of 200
{{{f(x) = 100 (1.08)^n }}}
{{{200 = 100 (1.08)^n }}}
{{{2 = (1.08)^n }}}

Plug in a few numbers and you'll find that about 9 years will double the population (that is a handy thing to know when calculating interest too. Remember the 'rule of 72'. Divide 72 by the interest rate (in this case 8) and see that is will take about 9 years to double.