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Question

Mathematics Question on Compound Interest

A firm anticipates an expenditure of ₹10,000 for a new equipment at the end of 5 years from now. How much should the firm deposit at the end of each quarter into a sinking fund earning interest 10% per year compounded quarterly to provide for the purchase?
[Use (1.025)20=1.7]

A

₹368.55

B

₹298.40

C

₹357.14

D

₹745.03

Answer

₹357.14

Explanation

Solution

The formula for sinking fund payments is:

A=S(1+r)n1rrA = \frac{S}{\left(1 + r\right)^n - 1} \cdot \frac{r}{r}

where AA is the periodic payment, SS is the future value (target amount), rr is the interest rate per period, and nn is the total number of periods.

Here:

S=10,000,r=0.025(quarterly interest rate),n=20(quarters).S = 10,000, \quad r = 0.025 \, (\text{quarterly interest rate}), \quad n = 20 \, (\text{quarters}).

The sinking fund factor is:

(1.025)2010.025=1.710.025=0.70.025=28.\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=10,00028=357.14.A = \frac{10,000}{28} = 357.14.

Thus, the firm should deposit Rs. 357.14 at the end of each quarter.