The interest rate Mr Frank must invest his money is at 10% per year compounded monthly
That is option 1.
Calculation of interest rates
The amount for Mr Frank's son school fees = R60 000.00
Cash at hand( principal amount) = R46 150.30
Therefore the simple interest needed to make up R60 000.00= R60 000.00 - R46 150.30= 14,849.70
Time of investment = 3 years
Therefore the rate = simple interest × 100/ principal×time
Rate (R) = 14,849.70 × 100/ 46 150.30× 3
= 1,484,970/135,450.9
= 10.0%
Therefore, the interest rate Mr Frank must invest his money is at 10% per year compounded monthly.
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