Let the principal amount be \( P \) and the rate of interest be \( R % \).
Step 1: Use the simple interest formula to find the principal.
The simple interest formula is:
\[
SI = \frac{P \times R \times T}{100}
\]
Given that \( SI = 2,550 \) and \( T = 8 \) years, we can substitute these values into the formula:
\[
2,550 = \frac{P \times R \times 8}{100}
\]
Simplifying:
\[
2,550 = \frac{8P \times R}{100} \quad \Rightarrow \quad 2,550 \times 100 = 8P \times R \quad \Rightarrow \quad 255,000 = 8P \times R
\]
\[
P \times R = \frac{255,000}{8} = 31,875
\]
Step 2: Increase the rate by 3%.
The new rate of interest becomes \( R + 3 \). The interest with this increased rate can be calculated as:
\[
SI_{\text{new}} = \frac{P \times (R + 3) \times 8}{100}
\]
Substitute \( P \times R = 31,875 \) into the formula:
\[
SI_{\text{new}} = \frac{31,875 \times 8 + 3 \times P \times 8}{100}
\]
We can see that to calculate the new simple interest, we need to know the exact value of \( P \). Since we don`t have enough information to determine the principal \( P \), the new interest can`t be determined.
Final Answer: The correct answer is (d) Can`t be determined.