At the end of each quarter a payment of K500 is made into an account which bearing interest compounded quarterly. If the annuity accrues to K7500 over three years, determined the nominal interest rate.

1 answer

To determine the nominal interest rate, we need to use the formula for the future value of an annuity:

\[FV = P \times \left(1 + \frac{r}{n}\right)^{nt} - P\]

Where:
FV = Future value of the annuity (K7500)
P = Quarterly payment (K500)
r = nominal interest rate
n = number of compounding periods per year (4 for quarterly compounding)
t = number of years (3 years)

Substitute the values into the formula:

\[7500 = 500 \times \left(1 + \frac{r}{4}\right)^{4*3} - 500\]

Simplify the equation:

\[7500 = 500 \times \left(1 + \frac{r}{4}\right)^{12} - 500\]

\[8000 = \left(1 + \frac{r}{4}\right)^{12}\]

Taking the 12th root of both sides:

\[1 + \frac{r}{4} = \sqrt[12]{8000}\]

\[1 + \frac{r}{4} \approx 1.1089\]

\[\frac{r}{4} \approx 0.1089\]

\[r \approx 0.4356\]

Therefore, the nominal interest rate is approximately 43.56%.