Question:

A man takes a loan of 1000 and repays it by paying 530 at the end of the first year, and 594 at the end of the second year. Find the rate of interest per annum.

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In loan installment problems with multiple-choice options, back-solving by plugging in the given interest rates is almost always faster than solving the algebraic equation.
Updated On: Nov 30, 2025
  • 8%
  • 10%
  • 12%
  • 9%
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The Correct Option is A

Solution and Explanation

Step 1: Understanding the Question:
The problem describes a loan that is paid back in two installments over two years. The interest is compounded annually. We need to find the annual interest rate. The principle is that the present value of all the repayments must equal the initial loan amount.
Step 2: Key Formula or Approach:
The present value (PV) of a future amount (FV) paid after \(n\) years at an annual interest rate \(r\) is given by the formula:
\[ PV = \frac{FV}{(1+r)^n} \] The total loan amount must be equal to the sum of the present values of all installments.
\[ \text{Loan Amount} = \frac{\text{Installment}_1}{(1+r)^1} + \frac{\text{Installment}_2}{(1+r)^2} \] Step 3: Detailed Explanation:
Given:
- Loan Amount = 1000
- Installment at the end of year 1 = 530
- Installment at the end of year 2 = 594
Let the annual interest rate be \(r\). The equation is:
\[ 1000 = \frac{530}{(1+r)} + \frac{594}{(1+r)^2} \] Solving this equation directly would result in a quadratic equation, which can be time-consuming. A more efficient method for competitive exams is to test the given options.
Testing Option (A) 8%:
If \(r = 8% = 0.08\), then \(1+r = 1.08\).
Let's calculate the sum of the present values of the installments:
\[ PV = \frac{530}{1.08} + \frac{594}{(1.08)^2} \] \[ PV = \frac{530}{1.08} + \frac{594}{1.1664} \] \[ PV = 490.7407... + 509.259... \] \[ PV \approx 999.999... \] This value is approximately equal to 1000. Therefore, the interest rate is 8%.
Testing Option (B) 10%:
If \(r = 10% = 0.10\), then \(1+r = 1.1\).
\[ PV = \frac{530}{1.1} + \frac{594}{(1.1)^2} = \frac{530}{1.1} + \frac{594}{1.21} \] \[ PV = 481.81 + 490.90 = 972.71 \] This is not equal to 1000.
The other options will also not yield 1000.
Step 4: Final Answer
By substituting the options into the present value formula, we find that an interest rate of 8% correctly equates the present value of the repayments to the loan amount.
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