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

A sum of money, lent out at simple interest, doubles itself in $8$ years. Find in how many years will the sum become triple (three times) of itself at the same rate per cent ?
  1. $11$ years
  2. $13$ years
  3. $14$ years
  4. $16$ years
Reveal answer Fill a bubble to check yourself
D Correct answer
Explanation

Simple interest doubles in 8 years, meaning the interest earned equals the principal in 8 years. To triple the sum, the interest must be twice the principal. Since interest is proportional to time, it takes 16 years to earn twice the principal.

Multiple choice

A man has Rs. $10,000$ to invest. He invests Rs. $4000$ at $5\%$ per annum and Rs. $3500$ at $4\%$ per annum simple interest. At what rate of interest per annum should he invest the remaining amount in order to have an yearly income of Rs. $500$
  1. $12\%$ p.a.
  2. $6.4\%$ p.a.
  3. $8\%$ p.a.
  4. $13.6\%$ p.a.
Reveal answer Fill a bubble to check yourself
B Correct answer
Explanation

Total investment is 10000. Remaining amount is 10000 - 4000 - 3500 = 2500. Interest from first part is 4000 * 0.05 = 200. Interest from second part is 3500 * 0.04 = 140. Total interest needed is 500, so interest from third part must be 500 - 200 - 140 = 160. Rate = (160 / 2500) * 100 = 6.4%.

Multiple choice

A sum of Rs $1550$ was lent partly at $5 $% p.a. and partly at $8$% p.a. simple interest. The total interest received after $3$ years is Rs $ 300$. What is the ratio of the money lent at $5$% to that at $8$% ?
  1. $12 : 13$
  2. $11 : 13$
  3. $16 : 15$
  4. $19 : 15$
Reveal answer Fill a bubble to check yourself
C Correct answer
Explanation

Let x be the amount at 5% and (1550 - x) be the amount at 8%. Interest = (x * 0.05 * 3) + ((1550 - x) * 0.08 * 3) = 300. 0.15x + 372 - 0.24x = 300. -0.09x = -72. x = 800. The amount at 8% is 1550 - 800 = 750. Ratio 800:750 = 16:15.

Multiple choice

Shruti lent some money to Pallavi at 5% p.a. simple interest. Pallavi lent the whole amount to Niki on the same day at $\displaystyle 8\frac{1}{2}$% p.a. In this transaction after a year Pallavi earned a profit of Rs 350. Find the sum of money lent by Shruti to Pallavi.
  1. Rs $9000$
  2. Rs $10000$
  3. Rs $8500$
  4. Rs $10200$
Reveal answer Fill a bubble to check yourself
B Correct answer
Explanation

Let P be the principal. Interest. Pallavi earns (8.5% - 5%) = 3.5% on the principal. 3.5% of P = 350. P = 350 / 0.035 = 10000.

Multiple choice

Two equal sums of money were invested, one at $4\%$ and the other at $\displaystyle 4\frac{1}{2}$%. At the end of $7$ years, the simple interest received from the latter exceeded that received from the former by Rs. $31.50$ Each sum was
  1. Rs. $1000$
  2. Rs. $500$
  3. Rs. $750$
  4. Rs $900$
Reveal answer Fill a bubble to check yourself
D Correct answer
Explanation

Let sum be P. Interest 1 = P * 0.04 * 7 = 0.28P. Interest 2 = P * 0.045 * 7 = 0.315P. Difference = 0.035P = 31.50. P = 31.50 / 0.035 = 900.