When a partner withdraws a fixed amount at the end of every quarter, the average period for calculating interest is generally 7½ months. However, in this specific case, interest charged on Mishu's drawings amounted to ₹9,000, which reflects an average period of 4½ months instead of the usual average of 7½ months.
Step 1: Verify the given interest amount:
Interest on drawings formula: \[ \text{Interest} = \text{Total Drawings} \times \text{Rate of Interest} \times \frac{\text{Average Period}}{12}. \] Given that the total interest is ₹9,000 and the rate of interest is \(15\%\), the shorter average period of 4½ months can be confirmed based on the actual interest charged.
Conclusion:
Interest on Mishu's drawings was calculated for an average period of \(4½ \ \text{months}\).

A ladder of fixed length \( h \) is to be placed along the wall such that it is free to move along the height of the wall.
Based upon the above information, answer the following questions:
(iii) (b) If the foot of the ladder, whose length is 5 m, is being pulled towards the wall such that the rate of decrease of distance \( y \) is \( 2 \, \text{m/s} \), then at what rate is the height on the wall \( x \) increasing when the foot of the ladder is 3 m away from the wall?