Answer
$\$ 118.12$
Work Step by Step
A sinking fund is an account earning compound interest into which you make periodic deposits. $\\$
$FV=PMT\displaystyle \cdot\frac{(1+i)^{n}-1}{i}, \quad PMT=FV\cdot\frac{i}{(1+i)^{n}-1}$
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given: $\\$
$t=10$ years,
annual rate: r =$0.03$
m=$12 \ \ \ $compounding periods per year,
$\displaystyle \mathrm{i}=\frac{r}{m}=\frac{0.03}{12}=0.0025 \ \ $(rate per compounding period$)$
$n=mt=120 \ \ $(total number of periods)
During this time, the initial $PV=10,000$ will grow to
$FV_{0}=PV(1+\displaystyle \frac{r}{m})^{mt}=10,000(1+\frac{0.03}{12})^{120}\approx 13,493.54$
which leaves
$FV=30,000-13,493.54=16,506.46$
for the sinking fund
$PMT=FV\displaystyle \cdot\frac{i}{(1+i)^{n}-1}$
$=16,506.46\displaystyle \cdot\frac{0.0025}{(1+0.0025)^{120}-1}$
$\approx$118.121489397