Compound interest : Quiz

1. A sum of money becomes Rs.6690 after three years and Rs.10,035 after 6 years on compound interest. The sum is :

a. Rs.4400

b. Rs.4445

c. Rs.4460

d. Rs.4520

e. Rs.4978

2. Rs.1600 at 10% per annum compound interest compound half-yearly amount to Rs.1944.81  in 

a. 2 years

b. 3 years

c..1.5years

d. 2.5 years

e. 3 years

3. The difference between simple interest and compound interest on a sum for 2 years at 8%, when the interest is compounded annually Rs.16. If the interest was compounded half-yearly, the difference in two interests would be nearly :

a. Rs.16

b. Rs.16.80

c. Rs.21.85

d. Rs.24.64

e. Rs. 25

4. The difference in C.I and S.I for 2 years on a sum of money is Rs.160. If the S.I for 2 years be Rs.2880, the rate percent is :

a. 105/9%

b. 100/8%

c. 100/9%

d. 9%

e. 10%

5. The value k of a machine depreciates every year at the rate of 10% on its value at the beginning of that year. If the present value of the machine is Rs.729, its worth 3 years ago was :

a. Rs.947.10

b. Rs.800

c. Rs.1000

d. Rs.750.87

e. Rs. 789.67

6. The least number of complete years in which a sum of money put out at 20% C.I. will be more than doubled is :

a. 3

b. 4

c. 5

d. 6

e. 7

7. A sum of Rs.550 was taken a loan. This is to be repaid in two equal annual instalments. If the rate of interest be 20% compounded annually, then the value of each instalment is :

a. Rs.421

b. Rs.396

c. Rs.360

d. Rs.350

e. Rs. 457

8. A loan was repaid in two annual instalments of Rs.112 each. If the rate of interest be 10% per annum compounded annually, the sum borrowed was :

a. Rs.200

b. Rs.210

c. Rs.217.80

d. Rs.280

e. Rs. 290

9. A sum amounts to Rs.2916 in 2 years and to Rs.3149.28 in 3 years at compound interest. The sum is :

a. Rs.1500

b. Rs.2000

c. Rs.2500

d. Rs.3000

e. Rs. 3500

10.A sum of money amounts to Rs.10648 in 3 years and Rs.9680 in 2 years. The rate of interest is :

a. 5% 

b. 10%

c. 15%

d. 20%

e. 18%

Answers 

1. C

2.  A

3. D
For Ist year, S.I = C.I
Thus, Rs.16 is the S.I on S.I for 1 year, which at 8% is thus Rs.200
i.e.S.I on the principal for 1 year is Rs.200
Principal = Rs. (100×2008×1)=Rs.2500
Amount for 2 years, compounded half-yearly
=Rs.[2500×(1+4100)4]=Rs.2924.64
C.I = Rs.424.64
Also, S.I = Rs.(2500×8×2100)=Rs.400
Hence, [(C.I)-(S.I)] = Rs. (424.64-400)=Rs.24.64

4. C
S.I for 1 year = Rs.1440
S.I on Rs.1440 for 1 year = Rs.160
Hence, rate percent = 160*100/1440

5. C
6.B
7. C
8. B
Principal = (Present value of Rs.121 due 1 year hence ) + (Present value of Rs.121 due 2 years 

= Rs. 121(1+10/100)+121(1+10/100)2 =Rs.210

 9.C
10.B