# SIMPLE INTEREST COMPOUND INTERESTS PROBLEM WITH EXPLANATIONS

QUANTITATIVE APTITUDE SIMPLE COMPOUND INTEREST PRACTICE PROBLEM WITH SOLUTION

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SIMPLE INTEREST:
S. I = PTR / 100
S. I = Simple interest
P = principal
T = time in years
R = rate of interest
A = P + S. I
A = total amount

COMPOUND INTEREST:
C. I = P × (1 + R / 100)T – P

C.I = Compound interest
P = principal
T = time in years
R = rate of interest
A = P + C. I
A = Total amount

Compound interest for half-yearly
I = P × (1 + R/2 * 100)2T – P
Compound interest for quarterly
I = P × (1 + R/4 * 100)4T – P
When T = 2 years, R = any rate of interest
I – S. I = PR² / 100²
When T = 3 years, R = any rate of interest
I – S. I = PR² (300 + R) / 100³

Q. The difference between Compound and Simple rates of interest on 10, 000/- for 3 – years at 5% per annum is ………..
SOL:
SHORT METHOD
for Difference between C. I & S. I for 3 – years
C. I – S. I = PR² (300 + R) / 100³
= 10,000 * 5 * 5 * (300 + 5) / 100³

SHORT METHODS FOR COMPOUND INTEREST
When T = 2 years R = any rate of interest

For example R = 6%
C. I = P * 12.36 / 100 [ 12 = 6 + 6 ] [ 36 = 6 * 6 ]
I = Compound interest
P = principal
For example R = 8%
When T = 3 years, R = 3%
C. I = P × 9.2727 / 100

When = 3 years, R = 4%
C. I = P × 12.4864 / 100

When T = 3 years, R = 5%
C. I = P × 15.7625 / 100

When T = 3 years, R = 6%
C. I = P × 19.1016 / 100

When T = 3 years, R = 7%
C. I = P × 22.5043 / 100

When T = 3 years, R = 8%
C. I = P × 25.9712 / 100

When T = 3 years, R = 9%
C. I = P × 29.5029 / 100

When T = 3 years, R = 10%
C. I = P × 33.1 / 100

When T = 3 years, R = 11%
C. I = P × 36.7631 / 100

When T = 3 years, R = 12%
C. I = P × 40.4928 / 100

When T = 3 years, R = 13%
C. I = P × 44.2897 / 100

When T = 3 years, R = 14%
C. I = P × 48.1544 / 100

When T = 3 years, R = 15%
C. I = P × 52.0875 / 100

Practice Simple and Compound Interest Problems

1) On simple interest, any amount becomes 812/- in two years and 924/- in four years. What is the rate of interest on that amount?

2) A man deposits am amount of 54600/- at an S.I rate of 12% for 3 years. What total amount will he get at the end of 3 years?

3) A sum of money will become 108800/- in four years at 7% per annum on S.I. Find the sum ………..

4) A sum of money will become double in 3 years at a certain rate of C.I. In what time will it becomes four times itself ?

5) What will be the amount on 25000/- in 2 years at C.I if the rates for the successive years be 4% & 5% per year

6) The difference of S.I on 5000/- from two banks in 2 years is 100/-. Find the difference of their rate …

7) A sum becomes 3 times in 10 years. In how many years will amount to 5 times at the same rate of S.I

8) Find the sum which amount to 1125/- in 5 years and becomes 1200/- in 8 years at the rate of S.I ………

9) If 5, 000/- becomes 5, 700/- in one year, what will 7, 000/- become at the end of 5- years at the same rate of simple interest?

10) A sum of money 12, 000/- deposited at compound interest became double after 5- years. How much will it be after 20 years ?

11) If the difference between the C. I, compounded every 6 months and the S.I on certain sum of money at the rate of 12% p. a for one year is 36/-, the sum is?

12) Arun lends 20, 000/- to two of his friends. He gives 12, 000/- to the first one at 8% per annum at simple interest. Arun wants to make a profit of 10% on the whole. The simple interest rate at which he should lend the remaining sum of money to the second friend is…

13) An amount of money at C. I grow up to 3840/- in 4- years and up to 3956/- in 5- years. Find the rate of interest

14) A man borrows 21, 000/- at 10% compound interest. How much he has to pay equally at the end of each year, to settle his loan in two years is

15) 1, 500/- is invested at a rate of 10% S. I and interest is added to the principal after every 5- years. In how many years will it amount to 2, 500/-?

16) What annual payment will discharge a debt of 6450/- due in 4- years at 5% per annum simple interest?

17) A person invested in three banks in the ratio of 1: 2: 3 and the rates were in the ratio of 2: 3: 4 at S.I, also he got the income in the ratio of 3: 4: 5, then find the ratio of time periods

18) Person invested in all 2, 600/- at 4%, 6% and 8% per annum S.I. At the end of the year, he got the same interest in all three cases. The money invested at 4% is

19) A person has 5, 000/-. He invests a part of it at 3% per annum and the remainder at 8% per annum S.I. His total income I 3- years is 750/-. Find the sum invested at different rate of interest.

20) The S.I and C.I on a sum of money for are 8, 400/- and 8652/- respectively. The rate of interest per annum is

21) A sum of money invested at C.I amounts to 800/- in 2- years and 880/- in 3- years. Find the rate of interest per annum and the sum

22) A man borrows 3000/- at 10% compound rate of interest. At the end of each year he pays back 1000/-, how much amount should he pay at the end of the third year to clear all his dues.

23) A certain sum is invested for certain time. It amounts to 450/- at 7% per annum. But, when invested at 5% per annum, it amounts to 350/-. Find out the sum and time.

24) A sum 2/- is lent to be paid back in 3 equal monthly installments of 1/- each. Find the rate percent ….

25) A man borrows 3, 000/- at 10% compound interest per annum. At the end of each year, he pays back 1,000/-. How much amount he pay at the end of 3rd year to clear all his dues?

26) Divide 15, 494/- A and B so that A’s share at the end of 9 – years may be equals to B’s share at the end of 11 – years, Compound Interest being 20% per annum. Then A’s share is

27) The Simple Interest for 4 –years is one-fourth of the Principal. The sum that will be amount to 450/- in two years at the same rate is

28) Kartik lost 9% by selling pencils at the rate of 15 a rupee. How many for a rupee must Kartik sell them to gain 5%

Solutions for Practice Problems will be available on Fdaytalk Quantitative Aptitude Book, Download Here