Average monthly expenditure permitted = Rs. 500 Total expenditure permitted for 12 months = Rs. 500 × 12 = Rs. 6000 Expenditure incurred during the first nine months =Rs. 511 × 9 = Rs. 4,599 Expenditure for the last three month = Rs. (6000 – 4599) = Rs. 1,401 ∴ Average monthly expenditure for the three months = Rs.