Quantitative Aptitude

Simple and Compound Interest

3,394 Questions
All Simple interest and its inverse forms 768 Compound interest with annual compounding 742 Simple-interest growth and split sums 626 Difference between compound and simple interest 479 Half-yearly and quarterly compounding 252 Changing rates and fractional years 201 Installments (CI based) 190 Ratio of principal to interest 118 Population growth and depreciation 16

Simple and Compound Interest Questions

Multiple choice

Determine the principal if the difference between the compound and simple interest on a certain sum at $13\%$ per annum for $3$ years is Rs. $600$.
  1. $11363$
  2. $12363$
  3. $13363$
  4. $14363$
Reveal answer Fill a bubble to check yourself
A Correct answer
Explanation

The difference between CI and SI for 3 years is P * (r/100)^2 * (3 + r/100). With r = 13, the formula is 600 = P * (0.13)^2 * (3.13) = P * 0.0169 * 3.13 = P * 0.052897. P = 600 / 0.052897 approximately 11342.7. Option A is the closest value.

Multiple choice

An account earns $7$ percent interest that is compounded annually. If $ $400$ were invested in the account for $x$ years, find the smallest possible integral value of $x$ such that at the end of $x$ years, the amount in the account will be at least $3$ times the initial investment.
  1. $14$
  2. $15$
  3. $16$
  4. $17$
Reveal answer Fill a bubble to check yourself
D Correct answer
Explanation

The amount A = P(1 + r)^x. We want A >= 3P, so (1.07)^x >= 3. Using logarithms, x * log(1.07) >= log(3). x >= log(3) / log(1.07) approx 0.4771 / 0.0294 approx 16.23. The smallest integral value is 17.