The formula for sinking fund payments is:
\(A = \frac{S}{\left(1 + r\right)^n - 1} \cdot \frac{r}{r}\)
where \(A\) is the periodic payment, \(S\) is the future value (target amount), \(r\) is the interest rate per period, and \(n\) is the total number of periods.
Here:
\(S = 10,000, \quad r = 0.025 \, (\text{quarterly interest rate}), \quad n = 20 \, (\text{quarters}).\)
The sinking fund factor is:
\(\frac{\left(1.025\right)^{20} - 1}{0.025} = \frac{1.7 - 1}{0.025} = \frac{0.7}{0.025} = 28.\)
The quarterly deposit is:
\(A = \frac{10,000}{28} = 357.14.\)
Thus, the firm should deposit Rs. 357.14 at the end of each quarter.