Answer
The deposits at the end of each month is $81
Work Step by Step
As the required interest per annum is \$60,000, so let the value of annuity will be \$120,000 that is double of the required interest amount.
Compute deposits at the end each month using formula as shown below:
\[\begin{align}
& P=\frac{A\left( \frac{r}{n} \right)}{\left[ {{\left( 1+\frac{r}{n} \right)}^{nt}}-1 \right]} \\
& =\frac{\$120,000\left(\frac{0.08}{12}\right)}{\left[{{\left(1+\frac{0.08}{12}\right)}^{12\times30}}-1\right]}\\&=\frac{\$120,000\left(0.00667\right)}{\left[{{\left(1+0.00667\right)}^{360}}-1\right]}\\&=\frac{\$800.4}{\left[{{\left(1.00667\right)}^{360}}-1\right]}\end{align}\]
\[\begin{align}
& =\frac{\$800.4}{10.94-1}\\&=\$80.52\\&\simeq\$81\end{align}\]
