A person spends Rs. 3,500 per month and saves 12 1/2% of income. What is the monthly income?

Introduction / Context:
This is a reverse calculation of income from given expenditure and savings rate. If savings are a fixed percentage of income, expenditure is the remainder. We use the complement of the saving rate to compute the income.

Given Data / Assumptions:

• Monthly spend = Rs. 3,500.
• Savings rate = 12 1/2% = 12.5% = 1/8 of income.
• Income = Spend + Save.

Concept / Approach:
If savings are 1/8 of income, then expenditure is 7/8 of income. So 7I/8 = 3,500 → I = 3,500 * 8 / 7. This avoids trial-and-error and yields an exact figure.

Step-by-Step Solution:

Verification / Alternative check:
Savings at 12.5% of 4,000 = 500; expenditure = 4,000 − 500 = 3,500, matching the given data.

Why Other Options Are Wrong:

• Rs. 4,400; Rs. 4,270; Rs. 3,937.50: These do not produce expenditure exactly Rs. 3,500 with a 12.5% saving rate.

Common Pitfalls:
Applying 12.5% on expenditure instead of income or mis-converting 12 1/2% to fraction.

Final Answer: