To calculate the interest on a principal amount of \(21400\) at an interest rate of \(3.5%\) per annum over a period of \(3.5\) years, you can use the simple interest formula:
\[ \text{Interest} = \text{Principal} \times \frac{\text{Rate}}{100} \times \text{Time} \]
In this case, the values are:
- Principal (\(P\)) = \(21400\)
- Rate (\(R\)) = \(3.5%\)
- Time (\(T\)) = \(3.5\) years
Substituting the values into the formula:
\[ \text{Interest} = 21400 \times \frac{3.5}{100} \times 3.5 \]
Calculating step-by-step:
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Calculate \(\frac{3.5}{100}\): \[ \frac{3.5}{100} = 0.035 \]
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Multiply by the time (3.5 years): \[ 0.035 \times 3.5 = 0.1225 \]
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Now multiply by the principal: \[ \text{Interest} = 21400 \times 0.1225 = 2617.50 \]
So, the interest earned over \(3.5\) years on \(21400\) at an interest rate of \(3.5%\) per annum is \(2617.50\).
Finally, if you want to know the total amount after \(3.5\) years, you can add the interest to the principal:
\[ \text{Total Amount} = \text{Principal} + \text{Interest} = 21400 + 2617.50 = 24017.50 \]
Thus, the total amount after \(3.5\) years is \(24017.50\).