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Question

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?

This question was previously asked in
RRB NTPC 2019 CBT 1 Question Paper (8-Mar-2021) (Shift 2)
The correct answer is
25%

The problem asks for the rate of interest (R) given the principal amount (P), time period (n), and the difference between Compound Interest (CI) and Simple Interest (SI) for 2 years.

Interest Rate Calculation: CI vs SI Difference

Given:

  • Principal (P) = ₹16,000
  • Time (n) = 2 years
  • Difference (CI - SI) = ₹1,000

Compound vs Simple Interest Formula

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

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

Where:

  • P is the principal amount
  • R is the annual rate of interest in percent

Solving for Rate of Interest

Substitute the given values into the formula:

$ 1000 = 16000 \left( \frac{R}{100} \right)^2 $

Now, we need to solve for R:

  1. Divide both sides by 16000: $ \frac{1000}{16000} = \left( \frac{R}{100} \right)^2 $
  2. Simplify the fraction: $ \frac{1}{16} = \left( \frac{R}{100} \right)^2 $
  3. Take the square root of both sides: $ \sqrt{\frac{1}{16}} = \frac{R}{100} $
  4. Calculate the square root: $ \frac{1}{4} = \frac{R}{100} $
  5. Solve for R: $ R = \frac{1}{4} \times 100 $ $ R = 25 $

Therefore, the rate of interest is 25% per annum.

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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. Find the compound interest on ₹1,200 at 12% p.a. for 6 months compounded quarterly.
  7. A sum of money was lent on compound interest. It became ₹500 at the end of the first year and ₹550 at the end of second year. Find the rate of compound interest per annum.
  8. A deposited ₹8,000 in a bank at 8% per annum simple interest. B deposited ₹6,000 at 10% compound interest per annum. After 3 years the difference between their interest will be:
  9. If a sum on compound interest becomes 4 times in 3 years, then with the same interest rate, the sum will become 64 times in:
  10. If the difference between the compound interest and the simple interest on a certain sum of money at 8 % p.a. for 2 years is ₹240, then the sum of money is:

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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