On retirement, a woman receives Rs 1,45,440 from her provident fund and invests the entire amount in a scheme that pays 20% simple interest per annum; based on this simple interest income, what fixed monthly amount will she receive as regular income from the investment?

Introduction / Context:
This aptitude question on simple interest connects retirement planning with regular income from a lump sum provident fund. The woman invests her entire retirement amount in a scheme that pays a fixed rate of simple interest per year. The key idea is that the interest earned in one year can be converted into a constant monthly income by dividing the annual interest by twelve months.

Given Data / Assumptions:
- Principal invested in the simple interest scheme = Rs 1,45,440. - Annual simple interest rate = 20 percent per annum. - Interest is calculated using simple interest, not compound interest. - Required quantity is the fixed monthly income generated only from interest, with the principal assumed to remain invested.

Concept / Approach:
The basic simple interest formula is SI = (P * R * T) / 100, where P is principal, R is annual rate of interest in percent, and T is time in years. Here we first compute the simple interest for one year, because the rate is given per annum. Once we know the yearly interest, we divide it by 12 to find the monthly interest income, which equals the fixed monthly income from the scheme.

Step-by-Step Solution:
Step 1: Identify principal P = Rs 1,45,440. Step 2: Identify annual rate R = 20 percent per annum. Step 3: For one year, T = 1 year. Step 4: Compute annual simple interest: SI = (P * R * T) / 100 = (1,45,440 * 20 * 1) / 100. Step 5: Calculate the value: 1,45,440 * 20 = 2,90,880, then divide by 100 to get SI = Rs 29,088 per year. Step 6: Convert this annual interest to monthly income by dividing by 12: monthly income = 29,088 / 12. Step 7: Perform the division: 29,088 / 12 = Rs 2,424 per month.

Verification / Alternative check:
We can verify by reversing the calculation. If she receives Rs 2,424 per month, then in one full year she receives 2,424 * 12 = 29,088 as interest. Dividing this annual interest by the principal 1,45,440 and multiplying by 100 gives the annual rate: (29,088 * 100) / 1,45,440 = 20 percent. This matches the given rate, so our monthly income value is consistent and correct.

Why Other Options Are Wrong:
Rs 2,380 is lower than the correct income and could arise from rounding or using an incorrect principal or rate. Rs 2,550 is higher than the correct amount and does not match the exact simple interest calculation at 20 percent. Rs 2,224 would correspond to a lower annual interest rate than 20 percent and therefore does not satisfy the given conditions. Only Rs 2,424 correctly corresponds to 20 percent simple interest on Rs 1,45,440.

Common Pitfalls:
A common mistake is to divide the principal directly by 12 instead of dividing the annual interest by 12. Some learners also forget that the rate is per year and may try to apply 20 percent directly on a monthly basis, which is incorrect in simple interest problems. Another error is rounding intermediate values instead of using exact arithmetic, which can lead to a different monthly figure. Careful use of the formula and proper conversion from yearly to monthly income avoids these issues.

Final Answer:
The fixed monthly income she receives from the simple interest investment is Rs 2,424.