Exercise 11A
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Q1 | Ex-11A | Class 8 | RS AGGARWAL | chapter 11 | Compound Interest | myhelper
Question 1:
Find the amount and the compound interest on Rs 2500 for 2 years at 10% per annum, compounded annually.
Answer 1:
Principal for the first year = Rs. 2500Interest for the first year = Rs. (2500×10×1100)= Rs. 250Amount at the end of the first year = Rs. (2500 +250 ) = Rs. 2750Principal for the second year = Rs. 2750Interest for the second year = Rs. (2750×10×1100)= Rs. 275Amount at the end of the second year = Rs. (2750 + 275) = Rs. 3025∴ Compound interest = Rs. (3025 - 2500) = Rs. 525
Q2 | Ex-11A | Class 8 | RS AGGARWAL | chapter 11 | Compound Interest | myhelper
Question 2:
Find the amount and the compound interest on Rs 15625 for 3 years at 12% per annum, compounded annually.
Answer 2:
Principal for the first year = Rs. 15625Interest for the first year = Rs. (15625×12×1100)= Rs. 1875Amount at the end of the first year = Rs. ( 15625 + 1875) = Rs. 17500Principal for the second year = Rs. 17500Interest for the second year = Rs. (17500×12×1100)= Rs. 2100Amount at the end of the second year = Rs. (17500 + 2100 )= Rs. 19600Principal for the third year = Rs. 19600Interest for the third year = Rs. (19600×12×1100)= Rs. 2352Amount at the end of the second year = Rs (19600 + 2352) = Rs. 21952∴ Compound interest = Rs. ( 21952 - 15625) = Rs. 6327
Q3 | Ex-11A | Class 8 | RS AGGARWAL | chapter 11 | Compound Interest | myhelper
Question 3:
Find the difference between the simple interest and the compound interest on Rs 5000 for 2 years at 9% per annum.
Answer 3:
Principal amount = Rs. 5000Simple interest = Rs. (5000×2×9100)= Rs. 900The compound interest can be calculated as follows:Principal for the first year = Rs. 5000Interest for the first year = Rs. (5000×9×1100)= Rs. 450Amount at the end of the first year = Rs. (5000 +450) = Rs. 5450Principal for the second year = Rs. 5450Interest for the second year = Rs. (5450×9×1100)= Rs. 490.5Amount at the end of the second year = Rs. (5450 +490.5) = Rs. 5940.5∴ Compound interest = Rs. ( 5940.5 - 5000) = Rs. 940.5
Now, difference between the simple interest and the compound interest
= (CI - SI) =Rs. (940.5 - 900)=Rs. 40.5
Q4 | Ex-11A | Class 8 | RS AGGARWAL | chapter 11 | Compound Interest | myhelper
Question 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?
Answer 4:
Principal for the first year = Rs. 25000Interest for the first year = Rs. (25000×8×1100)= Rs. 2000Amount at the end of the first year = Rs. (25000 +2000) = Rs. 27000Principal for the second year = Rs. 27000Interest for the second year = Rs. (27000×8×1100)= Rs. 2160Amount at the end of the second year = Rs. (27000 +2160) = Rs. 29160Therefore, Ratna has to pay Rs. 29160 after 2 years to discharge her debt.
Q5 | Ex-11A | Class 8 | RS AGGARWAL | chapter 11 | Compound Interest | myhelper
Question 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.
Answer 5:
Principal amount = Rs. 20000Simple interest = Rs. (20000×2×12100)= Rs. 4800The compound interest can be calculated as follows: Principal for the first year = Rs. 20000Interest for the first year = Rs. (20000×12×1100)= Rs. 2400Now, amount at the end of the first year = Rs. (20000 + 2400)= Rs. 22400Principal for the second year = Rs. 22400Interest for the second year = Rs. (22400×12×1100)= Rs. 2688Now, amount at the end of the second year = Rs. (22400 + 2688) = Rs. 25088Hence, compound interest = Rs. ( 25088 - 20000) = Rs. 5088Now, CI - SI =Rs. (5088-4800)= Rs. 288∴ The amount of money Harpreet will gain after two years is Rs 288.
Q6 | Ex-11A | Class 8 | RS AGGARWAL | chapter 11 | Compound Interest | myhelper
Question 6:
Manoj deposited a sum of Rs 64000 in a post office for 3 years, compounded annually at 712% per annum. What amount will he get on maturity?
Answer 6:
Principal for the first year = Rs. 64000Interest for the first year = Rs. (64000×15×1100×2)= Rs. 4800Now, amount at the end of the first year = Rs.( 64000 +4800) = Rs. 68800Principal for the second year = Rs. 68800Interest for the second year = Rs. (68800×15×1100×2)= Rs. 5160Now, amount at the end of the second year = Rs. ( 68800 +5160) = Rs. 73960Principal for the third year = Rs. 73960Interest for the third year = Rs. (73960×15×1100×2)= Rs. 5547Now, amount at the end of the third year = Rs. (73960 +5547) = Rs. 79507∴ Manoj will get an amount of Rs.79507 after 3 years.
Q7 | Ex-11A | Class 8 | RS AGGARWAL | chapter 11 | Compound Interest | myhelper
Question 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.
Answer 7:
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 = Rs. (6250×4×1100)= Rs. 250Now, amount at the end of the first half year = Rs. (6250 +250) = Rs. 6500Principal for the second half year = Rs. 6500Interest for the second half year = Rs. (6500×4×1100)= Rs. 260Now, amount at the end of the second half year = Rs (6500 + 260) = Rs. 6760∴ Compound interest = Rs (6760 - 6250) = Rs 510Hence, Divakaran gets a compound interest of Rs 510.
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Q8 | Ex-11A | Class 8 | RS AGGARWAL | chapter 11 | Compound Interest | myhelper
Question 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 112 years?
Answer 8:
Principal amount = Rs. 16000Rate of interest = 10% per annum = 5% for half yearTime = 112 years = 3 half years
Principal for the first half year = Rs. 16000Interest for the first half year = Rs. (16000×5×1100)= Rs. 800Now, amount at the end of the first half year = Rs. (16000 + 800) = Rs. 16800Principal for the second half year = Rs. 16800Interest for the second half year = Rs. (16800×5×1100)= Rs. 840Now, amount at the end of the second half year = Rs. (16800 + 840) = Rs. 17640Principal for the third half year = Rs. 17640Interest for the third half year = Rs. (17640×5×1100)= Rs. 882Now, amount at the end of the third half year = Rs. (17640 + 882) = Rs. 18522∴ The amount of money Michael has to pay the finance company after 112years is Rs 18522.
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