4. (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 18 percent compounded monthly? Assume that you invest $1

today.

If you invest $1 at 18 percent compounded monthly, about how many years would it take for your investment to grow twofold to $2? (Hint: Remember to convert your calculator solution to years.) years (Round to one decimal place.)