Answer
${{\$}} 349,496.41$
Work Step by Step
THEOREM: Amount of an Annuity
Suppose that $P$ is the deposit in dollars made at the end of each payment period
for annuity paying i percent interest per payment period.
The amount $A$ of the annuity after $n$ deposits is$ A=P\displaystyle \frac{(1+i)^{n}-1}{i}$
$P=100$
$n=360$
$i=\displaystyle \frac{0.12}{12}=0.01$
$A=100\displaystyle \frac{(1.01)^{360}-1}{0.01}\approx 349,496.41$