Answer
$6.17\%$
Work Step by Step
The effective rate of interest ($r_e$), is given by the formula
$r_e=(1+\frac{r}{n})^n-1$
where $r$ is the annual interst rate and $n$ is the number of compounding periods per year.
Use the formula above to obtain:
$r_e=\left(1+\frac{0.06}{12}\right)^{12}-1\\ r_e=1.06167781186-1\\ r_e=0.06167781186\\ r_e \approx 6.17\%$
