SSC CHSL 15 Nov 2015 Shift 2 Paper

Average expenditure for the first 5 months = Rs. 1200
⇒ Total expenditure in first 5 months = $5\times 1200=\mathit{R}\mathit{s}.6000$
Similarly, total expenditure in next 7 months = $7\times 1300=\mathit{R}\mathit{s}.9100$
Total savings = Rs. 2900
Thus, total annual income = $6000+9100+2900=\mathit{R}\mathit{s}.18000$
∴ Monthly average income = $\frac{18000}{12}=\mathit{R}\mathit{s}.1500$