Question:
The aggregate monthly expenditure of a family was ₹ 18720 during the first 3 months, ₹ 20340 during the next 4 months and ₹ 21708 during the last 5 months of a year. If the total savings during the year be ₹ 35340 find the average monthly income of the family.
Solution:
The aggregate yearly expenditure of a family = Rs (18720 × 3) + Rs (20340 × 4) + Rs (21708 × 5)
= Rs (56160 + 81360 + 108540)
= Rs 246060
The total savings during the year = Rs 35340
The average yearly income = Rs 246060 + Rs 35340
= Rs 281400
$\therefore$ The average monthly income of the family $=\frac{281400}{12}=\mathrm{Rs} 23450$
Hence, The average monthly income of the family is Rs 23450 .