Monthly income from expenditures and savings: The average expenditure for the first 5 months is Rs 120 and for the next 7 months is Rs 130. If the man saves Rs 299 in the year, what is his average monthly income?
Aptitude
Average
Difficulty: Medium
Choose an option
Answer
Correct Answer: Rs 150.75
Explanation
Introduction / Context:Average income can be deduced from total expenditure plus total savings across the year. The problem provides averages for two blocks of months and the total annual savings.Given Data / Assumptions:
- First 5 months average spend = Rs 120
- Next 7 months average spend = Rs 130
- Annual savings = Rs 299
- Months in year considered = 12
Concept / Approach:Total income = total expenditure + total savings. Average monthly income = total income / 12.Step-by-Step Solution:
Expenditure for first 5 months = 5 * 120 = 600Expenditure for next 7 months = 7 * 130 = 910Total annual expenditure = 600 + 910 = 1510Total income = 1510 + 299 = 1809Average monthly income = 1809 / 12 = 150.75Verification / Alternative check:Average spend over 12 months = 1510/12. Adding average saving per month 299/12 yields 150.75. Same result.Why Other Options Are Wrong:
- Rs 150, Rs 160, Rs 170: Do not equal the exact computed average 150.75.
Common Pitfalls:Using an approximate value or rounding too early instead of keeping the exact fraction for the final average.Final Answer:
Rs 150.75