All Exams Test series for 1 year @ ₹349 only
Question

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?

This question was previously asked in
RRB NTPC 2019 CBT 1 Question Paper (8-Mar-2021) (Shift 2)
The correct answer is
$4\%$

Finding the Interest Rate

The problem asks for the annual interest rate (R) given the principal amount (P), time period (T), and the difference between compound interest (CI) and simple interest (SI) for that period.

Given Information:

  • Principal Amount, P = ₹15,000
  • Time Period, T = 2 years
  • Difference between CI and SI = ₹24

Formula for CI - SI Difference (2 years):

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

$ \text{CI} - \text{SI} = P \left( \frac{R}{100} \right)^2 $

Where:

  • P = Principal Amount
  • R = Annual Interest Rate (in percent)

Calculation Steps:

  1. Substitute the given values into the formula: $ 24 = 15000 \left( \frac{R}{100} \right)^2 $
  2. Rearrange the formula to solve for $ \left( \frac{R}{100} \right)^2 $: $ \left( \frac{R}{100} \right)^2 = \frac{24}{15000} $
  3. Simplify the fraction: $ \left( \frac{R}{100} \right)^2 = \frac{8}{5000} = \frac{1}{625} $
  4. Take the square root of both sides to find $ \frac{R}{100} $: $ \frac{R}{100} = \sqrt{\frac{1}{625}} $ $ \frac{R}{100} = \frac{1}{25} $
  5. Solve for R: $ R = \frac{100}{25} $ $ R = 4 $

Therefore, the rate of interest per annum is 4%.

Was this answer helpful?

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. 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?
  3. 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:
  4. Find the interest (in ₹) on ₹8,000 at 10% per annum compounded half yearly for $1\frac{1}{2}$ years.

  5. 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?
  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 ₹______.
Need Expert Advice?
Upcoming Exams
RRB ALP
July 28, 2026
RRB Group D
August 03, 2026
Test Series
RRB NTPC img
Railways
RRB NTPC Under Graduate 2026 New Mock Test Series
1459 Tests 2 Tests Free
215 Attempts
4.3(512)
English, Hindi, Telugu +7 More

Start Your Preparation with Prepp Mobile App

Download the app from Google Play & App Store
Download the app from Google Play & App Store
Prepp Mobile App