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Question

The difference between the compound interest and the simple interest on a certain amount at a rate of interest of 5% per annum for 2 years is ₹25. Find the amount.

This question was previously asked in
RRB NTPC 2019 CBT 1 Question Paper (8-Mar-2021) (Shift 2)
The correct answer is
₹10,000

Finding the Principal Amount Using Interest Difference

The problem asks us to find the principal amount (P) given the difference between compound interest (CI) and simple interest (SI) over 2 years is ₹25, at an annual interest rate (R) of 5%.

Understanding the Interest Difference Formula

For a period of 2 years, the difference between compound interest and simple interest is calculated using the formula:

Difference = $P \times \left(\frac{R}{100}\right)^2$

Where:

  • P = Principal Amount
  • R = Annual Interest Rate (%)

Applying the Formula

We are given:

  • Difference = ₹25
  • R = 5%

Substitute the known values into the formula:

$25 = P \times \left(\frac{5}{100}\right)^2$

Calculating the Principal Amount

  1. Simplify the fraction: $\frac{5}{100} = \frac{1}{20}$
  2. Square the fraction: $\left(\frac{1}{20}\right)^2 = \frac{1}{400}$
  3. Rewrite the equation: $25 = P \times \frac{1}{400}$
  4. Solve for P: $P = 25 \times 400$
  5. Calculate the final value: $P = 10000$

Therefore, the principal amount is ₹10,000.

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Similar Questions

  1. If the interest earned during the $2^{\text{nd}}$ year on a certain sum is ₹6,258, and the rate of interest is 20% per annum compounded annually, then the sum is:
  2. The difference between compound interest and simple interest, at the same rate, on an amount of ₹15,000 for 2 years is ₹24. What is the rate of interest per annum?
  3. There is 60% increase in an amount in 6 years at simple interest. What will be the compound interest of ₹10,000 after 3 years at the same rate?
  4. Simple interest on a sum of money, at $5\%$ per annum for 2 years, is ₹50. The compound interest on the same sum for the same period at the same interest rate is:
  5. Find the interest (in ₹) on ₹8,000 at 10% per annum compounded half yearly for $1\frac{1}{2}$ years.

  6. The difference between the compound interest and the simple interest accrued, at the same rate of interest, on an amount of ₹16,000 in 2 years was ₹1,000. What was the rate of interest percent per annum?
  7. Find the compound interest on ₹1,200 at 12% p.a. for 6 months compounded quarterly.
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Important Questions from Simple and Compound Intrest

  1. The difference between the simple interest and the compound interest, compounded annually, on a certain sum of money for 2 years at 16% per annum is ₹797. Find the sum (rounded off to the nearest integer).
  2. The difference between the compound interest, compounded annually and the simple interest if ₹17,700 is deposited at 4% rate of interest per annum for 2 years is:
  3. The difference between the simple interest and the compound interest, compounded annually, on a certain sum of money for 2 years at 10% per annum is $₹407$. Find the sum [rounded off to the nearest integer].
  4. The difference between the simple interest and the compound interest, compounded annually, on a certain sum of money for 2 years at 17% per annum is ₹967. Find the sum [rounded off to the nearest integer].

  5. When the difference between compound interest, compounded annually, and simple interest for three years is ₹217 at 10% interest per annum, the principal is ₹______.
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