(Solving for n with non-annual periods) Approximately how many years would it take for an investment to grow twofold if it were invested at 15 percent compounded monthly? Assume that you invest $1 today. If you invest $1 at 15 percent compounded monthly, about how many years would take for your investment to grow twofold to $2? (Hint: Remember to convert your calculator solution to years.) 9.6 years (Round to one decimal place.)