Of the 15 stalls at a district fair, 4 pay a daily rent of ₹1,200 each and 6 pay ₹900 each. The remaining 5 stalls all pay the same rent as one another. If the average daily rent across all 15 stalls is ₹1,000, what does each of those remaining stalls pay?

All 15 stalls together pay $15\times 1,000$ = ₹15,000 a day. The two known groups pay $4\times 1,200$ = ₹4,800 and $6\times 900$ = ₹5,400, that is ₹10,200 between them, so the last five pay 15,000 - 10,200 = ₹4,800 between them, or 4800/5 = ₹960 each. ₹1,000 assumes an unknown group must sit at the overall average; it need not, and here the other ten stalls together run slightly above it. ₹1,050 is the midpoint of ₹1,200 and ₹900, which is not what the remaining stalls pay. ₹4,800 is the total for the five stalls, one division short of the answer.