Compound interest questions

Compound interest is a great way to save money and make more of it over time. It involves reinvesting your accumulative interest earned, allowing your money to grow exponentially. Here are some aptitude questions and answers on compound interest to assist you in learning this concept and facing any relevant aptitude questions.

  1. Find the compound intrest on 15625 for 9 months at 16% compounded quarterly?

Answer: Option D

A=P\((1+\frac{\frac{r}{4}}{100})^{3} )\)

=15625\((1+\frac{\frac{16}{4}}{100})^{3} )\)

=15625\((1+\frac{4}{100})^{3} )\)

=15625\((\frac{104}{100})^{3} )\)


CI= Rs 17576-15625=Rs 1951

  1. The compound interest on a certain sum of money for 2 years is Rs. 52 and the simple interest for the same time at the same rate is Rs. 50. Find the rate %

Answer: Option C

SI for 2 years = 50, CI for 2 years = 52.
SI and CI are same for the first year,therefore, SI and CI for 1st year = Rs. 25.
CI for 2nd year = 52 – 25 = 27
The difference of RS 2 will be the interest on 1st years SI
R= \( \frac{2\times 100}{25} \) =8%

  1. A sum of money amounts to Rs.7500 after 3 years and to Rs.10,035 after 6 years on compound interest.find the sum?

Answer: Option B

Let the sum be Rs.P.then

\( P(1+\frac{R}{100})^3=7500 \)…(i) and

\( P(1+\frac{R}{100})^6=12500 \)…(ii)

On dividing,we get \( (1+\frac{R}{100})^3=\frac{12500}{7500}=\frac{5}{3} \)

Substituting this value in (i),we get:

\( P\times(\frac{5}{3})=7500 \)

Hence,the sum is rs.4500

  1. What is the difference between simple interest and compound interest for 2 years at 10% interest rate of Rs. 8000 / -?

Answer: Option A

Easy way

The difference between ordinary interest and compound interest over a period of 2 years on an amount = P \(\times (\frac{R}{100})^{2}\)

Difference = 8000 \(\times (\frac{10}{100})^{2}\)

= 8000\(\times \frac{10}{100} \times\frac{10}{100}\) = 80rs

  1. The difference between compound interest and simple interest on RS 5000 for 2 years at 4% per anuum is:

Answer: Option B

Principal = 5000

n = 2 yrs

r = 4%

Difference = P\(\times\){\(\frac{r}{100}\)}\(^{2}\)

\(\Rightarrow\) 5000\(\times\){\(\frac{4}{100}\)}\(^{2}\)

\(\Rightarrow\) 5000 \(\times\){\(\frac{1}{25^{2}}\)}

\(\Rightarrow\) 8