RS Aggarwal Solutions: Exercise 11A - Compound Interest | Mathematics (Maths) Class 8 PDF Download

 Page 1


Q u e s t i o n : 1
Find the amount and the compound interest on Rs 2500 for 2 years at 10% per annum, compounded annually.
S o l u t i o n :
Principal for the first year = Rs. 2500Interest for the first year = Rs. 
2500×10×1
100
= Rs. 250Amount at the end of the first year = Rs. 2500 +250  = Rs. 2750Principal for the second
Q u e s t i o n : 2
Find the amount and the compound interest on Rs 15625 for 3 years at 12% per annum, compounded annually.
S o l u t i o n :
Principal for the first year = Rs. 15625Interest for the first year = Rs. 
15625×12×1
100
= Rs. 1875Amount at the end of the first year = Rs.  15625 + 1875 = Rs. 17500Principal for the
Q u e s t i o n : 3
Find the difference between the simple interest and the compound interest on Rs 5000 for 2 years at 9% per annum.
S o l u t i o n :
Principal amount = Rs. 5000Simple interest = Rs. 
5000×2×9
100
= Rs. 900The compound interest can be calculated as follows: Principal for the first year = Rs. 5000Interest for the first 
Q u e s t i o n : 4
Ratna obtained a loan of Rs 25000 from the Syndicate Bank to renovate her house. If the rate of interest is 8% per annum, what amount will she have to pay to the bank after 2 years to
discharge her debt?
S o l u t i o n :
Principal for the first year = Rs. 25000Interest for the first year = Rs. 
25000×8×1
100
= Rs. 2000Amount at the end of the first year = Rs. 25000 +2000 = Rs. 27000Principal for the second
Q u e s t i o n : 5
Harpreet borrowed Rs 20000 from her friend at 12% per annum simple interest. She lent it to Alam at the same rate but compounded annually. Find her gain after 2 years.
S o l u t i o n :
Principal amount = Rs. 20000Simple interest = Rs. 
20000×2×12
100
= Rs. 4800The compound interest can be calculated as follows: Principal for the first year = Rs. 20000Interest for the
Q u e s t i o n : 6
Manoj deposited a sum of Rs 64000 in a post office for 3 years, compounded annually at 7
1
2
% per annum. What amount will he get on maturity?
S o l u t i o n :
Principal for the first year = Rs. 64000Interest for the first year = Rs. 
64000×15×1
100×2
= Rs. 4800Now, amount at the end of the first year = Rs. 64000 +4800 = Rs. 68800Principal for
Q u e s t i o n : 7
Divakaran deposited a sum of Rs 6250 in the Allahabad Bank for 1 year, compounded half-yearly at 8% per annum. Find the compound interest he gets.
S o l u t i o n :
Principal amount = Rs. 6250Rate of interest = 8 % per annum = 4 % for half yearTime = 1 year = 2 half yearsPrincipal for the first half year = Rs. 6250Interest for the first half year 
Q u e s t i o n : 8
Michael borrowed Rs 16000 from a finance company at 10% per annum, compounded half-yearly. What amount of money will discharge his debt after 1
1
2
 years?
S o l u t i o n :
Principal amount = Rs. 16000Rate of interest = 10 % per annum = 5 % for half yearTime = 1
1
2
 years = 3 half yearsPrincipal for the first half year = Rs. 16000Interest for the first half
          
          
                             
          
          
                        
          
          
                             
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