The formula for compound interest compounded semi-annually is:
\[
A = P \left( 1 + \frac{r}{2} \right)^{2t}
\]
where:
- \( P = 24,000 \) is the principal,
- \( r = 10% = 0.10 \) is the rate of interest,
- \( t = 1 \frac{1}{2} = 1.5 \) years.
First, calculate the amount \( A \):
\[
A = 24000 \left( 1 + \frac{0.10}{2} \right)^{2 \times 1.5} = 24000 \left( 1.05 \right)^{3}
\]
\[
A = 24000 \times 1.157625 = 27,786
\]
Now, compound interest \( CI \) is:
\[
CI = A - P = 27,786 - 24,000 = ₹ 3,786
\]
Therefore, the correct answer is ₹ 3,780 (closest to the correct calculation).