Compound Interest : Aptitude Test (65 Questions with Explanation)

1.

What would be the compound interest accrued on an amount of 10000 Rs. at the end of 2 years at the rate of 4 % per annum?

   A.) 816
   B.) 10846
   C.) 10816
   D.) 10916

Answer: Option 'A'

Given principal = 10000
No. of years = 2
Rate of interest = 4
Amount = P [ 1 + ( r / 100 )n]
= 10000 x [ 1 +( 4 / 100 )2]
= 10000 x ( 104 / 100 )2
= 10000 x ( 104 / 100 ) x ( 104 / 100 )
= 104 x 104
= 10816
Compound Interest = Amount - Principal

= 10816 - 10000
= 816

2.

What would be the compound interest accrued on an amount of 8000 Rs. at the end of 2 years at the rate of 5 % per annum?

   A.) 8920
   B.) 8820
   C.) 8780
   D.) 8810

Answer: Option 'A'

Given principal = 8000.
No. of years = 2
Rate of interest = 5.
Amount = P x (1+r/100)n,
we get Amount = 8000 x (1+5/100)2 .
Ans : 8820

3.

What will be the amount if sum of Rs.10,00,000 is invested at compound interest for 3 years with rate of interest 11%, 12% and 13% respectively?

   A.) Rs.14,04,816
   B.) Rs.16,00,816
   C.) Rs 12,14,816
   D.) Rs. 11, 13,816

Answer: Option 'A'

Given
Here, P = Rs.10,00,000, R1 = 11 , R2 = 12, R3 = 13.
Each rate of interest is calculated for one year.
Hence, N = 1 year.
Amount after 3 years,
= P(1 + R1/100) (1 + R2/100) (1 + R3/100)
= 10,00,000 × (1 + 11/100) × (1 + 12/100) × (1 + 13/100)
= 10,00,000 × (111/100) × (112/100) × (113/100)
= 111 x 112 x 113
= 14,04,816
Hence the total amount after 3 years is Rs.14,04,816

4.

What would be the compound interest accrued on an amount of 6500 Rs. at the end of 2 years at the rate of 15 % per annum?

   A.) 2046.25
   B.) 2056.25
   C.) 2096.25
   D.) 2076.25

Answer: Option 'C'

Given principal = 6500
No. of years = 2
Rate of interest = 15
Amount = P x (1+r/100)n,
we get Amount = 6500 x (1+15/100)2 = 8596.25
C.I = Amount - Principal = 8596.25 - 6500 = 2096.25

5.

Find the simple interest on Rs. 1920 at 45 % per annum for 3 months

   A.) Rs. 196
   B.) Rs. 216
   C.) Rs. 206
   D.) Rs. 306

Answer: Option 'B'

Given
Principal : 1920
Rate of interest : 45
Number of months : 3
Simple interest for 1 year = pnr / 100
= ( 1920 x 1 x 45 ) / 100
= 864
Simple interest for 3 months = ( 3 / 12 ) x SI for 1 year
= ( 3 / 12 ) x 864
216

6.

What would be the compound interest accrued on an amount of 12500 Rs. at the end of 3 years at the rate of 10 % per annum?

   A.) 4137.5
   B.) 4537.5
   C.) 4237.5
   D.) 4337.5

Answer: Option 'A'

Given principal = 12500
No. of years = 3
Rate of interest = 10
Amount = P x (1+r/100)n,
We get Amount = 12500 x (1+10/100)3 = 16637.5
C.I = Amount - Principal = 16637.5 - 12500 = 4137.5

7.

Rs. 10000 is borrowed at compound interest at the rate of 4 % annum. What will be the amount to be paid after 2 years?

   A.) 10816
   B.) 10800
   C.) 10808
   D.) 10826

Answer: Option 'A'

Principal : P = 10000 Rs.
Rate of Interest : r = 4 %
Number of years : n = 2
Amount = P x (1 + r/100)n
Amount = 10000 x (1+4/100)2
=10000 x (1+1/25)2
=10000 x (26/25) x (26/25) =10816

8.

What would be the compound interest accrued on an amount of 5000 Rs. at the end of 2 years at the rate of 9 % per annum?

   A.) 940.5
   B.) 5940.5
   C.) 5990.5
   D.) 980.5

Answer: Option 'A'

Given principal = 5000
No. of years = 2
Rate of interest = 9 
Amount = P x (1+r/100)n,
We get Amount = 5000 x (1+9/100)2 = 5000 x (109/100) x (109/100) = 5940.5
Compound Interest, C. I = Amount - Principal = 5940.5 - 5000 = 940.5

9.

What would be the compound interest accrued on an amount of 12500 Rs. at the end of 3 years at the rate of 10 % per annum?

   A.) 4537.5
   B.) 4137.5
   C.) 6637.5
   D.) 6647.5

Answer: Option 'B'

Given principal = 12500
No. of years = 3
Rate of interest = 10
Amount = P x (1+r/100)n
= 12500 x (1+10/100)3
= 12500 x (11/10)3
= 12500 x (11/10)x (11/10)x (11/10)
= 16637.5
Compound Interest, C. I = Amount - Principal = 16637.5 - 12500 = 4137.5

10.

A person receives a sum of Rs. 2100 as interest for investing some amount at 10% p.a compounding annually for 2 years. Find the amount invested at the beginning

   A.) 10000
   B.) 9000
   C.) 10500
   D.) 9500

Answer: Option 'A'

Given Compound Interest = Rs.2100
Rate of Interest ( r ) = 10 % p.a
No.of years ( n ) = 2
To find , amount received at the beginning => principal
Compound Interest = P [ 1 + ( r / 100 )n- 1 ]
=> 2100 = P[ 1 + ( 10 / 100 )2- 1 ]
=> 2100 = P[ 1 + ( 1 / 10 )2- 1 ]
=> 2100 = P[ ( 11 / 10 )2- 1 ]
=> 2100 = P[ ( 121 / 100 ) - 1 ]
=> 2100 = P[ 21 / 100 ]
=> 2100 x ( 100 / 21 ) = P
Principal = Rs. 10000
Amount invested at the beginning = Rs. 10000

11.

Find the simple interest on Rs. 1300 at 10 % per annum for 5 years

   A.) Rs. 650
   B.) Rs. 550
   C.) Rs. 525
   D.) Rs. 615

Answer: Option 'A'

Given
Principal : 1300
Rate of interest : 10
Number of years : 5
Simple Interest = pnr / 100
Simple Interest = (1300 x 5 x 10) / 100
= 13 x 5 x 10
= 650 
So,Simple Interest = 650

12.

John invested an amount of Rs. 20000 for 2 years at compound interest at the rate of 6 % per annum. Find the amount he receives at the end of 2 years.  

   A.) 22472
   B.) 22000
   C.) 22372
   D.) 22120

Answer: Option 'A'

Given
Principal : P = 20000 Rs. Rate of Interest : r = 6 % Number of years : n = 2
Amount = P x (1 + r/100)n 
Amount = 20000 x (1+6/100)2
= 20000 x (1+3/50)2
= 20000 x (53/50) x (53/50)
22472.

13.

What would be the compound interest accrued on an amount of 14000 Rs. at the end of 3 years at the rate of 5 % per annum?

   A.) 16206.75
   B.) 2206.75
   C.) 15216.75
   D.) 16216.75

Answer: Option 'B'

Given
principal = 14000
No. of years = 3
Rate of interest = 5
Amount = P x (1+r/100)n
we get Amount = 14000 x (1+5/100)3
= 14000 x (105 / 100)3
= 14000 x (21 / 20)3
= 14000 x (9261 / 8000)
= 64827 / 4
16206.75
compound interest = Amount - principal
=16206.75 -14000
=2206.75

14.

Certain loan amount was repaid in two annual installments of Rs.1331/- each. If the rate of interest be 10% per annum Compounded annually the sum borrowed was?

   A.) Rs.121/-
   B.) Rs.2130/-
   C.) Rs.2310/-
   D.) Rs.1331/-

Answer: Option 'C'

Principal = (P.W of Rs. 1331/- due 1 year hence) + (P.W of Rs. 1331/- due 2 years hence) 
= [1331/(1 + 10/100) + 1331/(1 + 10/100)2
= [1331/(110/100) + 1331/(110/100 × 110/100)]
= 13310/11 + 133100/121 = 1210 + 1100 = Rs.2310/-

15.

Mr. Joshua invested Rs 15,000 divided into two different schemes A and B at S.I of 5% and 10%. If the total amount of the simple interest earned in 2 years is 2500, What was the amount invested in scheme B. 

   A.) 25,000
   B.) 10,000
   C.) 15,500
   D.) 30,000

Answer: Option 'B'

Given Total Principal = Rs. 15,000
Number of years = 2 years
Total S.I at the end of 2 years = Rs. 2500

For scheme A, Amount invested = x Rs.
Rate of interest, r = 5%

For scheme B, Amount invested= (15,000 - x) Rs.
Rate of interest, r = 10%

W.K.T: S.I = p * n * r / 100
=> S.I for scheme A + S.I for scheme B = Rs. 2500
=> {(x * 2 * 5)/ 100} + {(15,000 - x) * 2 * 10/ 100} = 2500
=> (x / 10) + 2(15,000 - x)/ 10 = 2500
=> (x/ 10) + (30,000 - 2x) /10 = 2500
=> x + 30,000 - 2x = 2500 * 10
=> 30,000 - x = 25000
=> x = 30,000 - 25,000
=> x= 5,000

For scheme B, Amount invested = (15,000 - x) Rs.
= 15,000 - 5,000
= 10,000 Rs.

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