Final answer:
Calculating the original interest rate from the given data, the rate is found to be 6.25%. With an increase of 3/4%, the new rate becomes 7%. The total interest on Rs 800 for 4 years at 7% interest rate is Rs 224. However, the available options do not match this result, indicating there may be missing information or a discrepancy in the question.
Step-by-step explanation:
We need to calculate the interest received on an amount of rs 800 when the rate of interest is increased by 3/4%. First, let's determine the original rate of interest from the provided data: Rs 600 becomes Rs 750 in 4 years.
Using the simple interest formula:
I = PRT/100
Where I is the interest, P is the principal amount, R is the rate, and T is the time in years.
The interest I on Rs 600 for 4 years is Rs 750 - Rs 600 = Rs 150.
Now, plugging the values into the formula:
150 = (600 * R * 4) / 100
R = (150 * 100) / (600 * 4) = 6.25%
The new rate of interest is 6.25% + 3/4% = 7%.
To calculate the new interest on Rs 800 for 4 years at 7%:
I = (800 * 7 * 4) / 100 = Rs 224
The total interest earned on Rs 800 at 7% per annum over 4 years is Rs 224. However, as we are not given the compounding frequency or if it is simple interest, we cannot compare the options provided directly, and thus the information provided does not match the question.