Mohan withdraws ₹4,000 at the beginning of each quarter.
\[
\text{Total Drawings} = 4,000 \times 4 = 16,000
\]
For drawings made at the beginning of each quarter, the average period is:
\[
\frac{12 + 9 + 6 + 3}{4} = 7.5 \text{ months}
\]
\[
\text{Interest on Drawings} = 16,000 \times \frac{6}{100} \times \frac{7.5}{12}
= ₹600
\]