Sohan borrows money on compound interest and returns it in two equal half - yearly instalments of $\text{Rs. 4,410}$ each. Find the interest charged if the rate of interest is $10 \%$ p.a. compounded half-yearly.
- $\text{Rs. 630}$
- $\text{Rs. 620}$
- $\text{Rs. 640}$
- $\text{Rs. 680}$