Answer
$ 10.47\%$
Work Step by Step
The effective interest rate $r_{eff}$ of an investment$\\$
paying a nominal interest rate of $r_{nom}=10\%=0.10\\\\$
compounded m$=12 \ \ \ \ $ times per year is$\\$
$r_{eff}=(1+\displaystyle \frac{r_{nom}}{m})^{m}-1$
$=(1+\displaystyle \frac{0.1}{12})^{12}-1\approx$0.104713067441$\\\\$
Rounded to the nearest $ 0.01\%$ (4th decimal place):
$ r_{eff}=10.47\%$