# RS Aggarwal Class 8 Math Eleventh Chapter Compound Interest Exercise 11A Solution

## EXERCISE 11A

**(1) Find the amount and the compound interest on Rs 2500 for 2 years at 10% per annum, compounded annually.**

Solution: Rate of interest = 10% per annum

Time = 2 years = 4 half-years

Original principle = Rs 2500

**(2) Find the amount and the compound interest on Rs 15625 for 3 years at 12% per annum, compounded annually.**

Solution: Rate of interest = 12% per annum

Time = 3 years

Original principle = Rs 15625

Amount at the end of the third year = Rs (19600 + 2352) = Rs 21952

∴ Compound interest = Rs (21952 – 15625) = Rs 6327.

**(3) Find the difference between the simple interest and the compound interest on Rs 5000 for 2 years at 9% per annum.**

Amount 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 compound interest = Rs (940.5 – 900) = Rs 40.5

**(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 blank after 2 years to discharge her debt?**

Solution: Rate of interest = 8% per annum

Time = 2 years

Original principle = Rs 25000

Amount at the end of the second year = Rs (27000+ 2160) = Rs 29160

Therefore, she has to pay Rs 29160 to the blank after 2 years to discharge her debt

**(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.**

Amount at the end of the second year = Rs (22400 + 2688) = Rs 25088

∴ Compound interest = Rs (25088 – 20000) = Rs 5088

Now, CI – SI = Rs (5088 – 4800) = Rs 288

**(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?**

Amount at the end of the second year = Rs (68800 + 5160) = Rs 73960

Principle for the third year = Rs 73960

Amount at the end of the third year = Rs (73960 + 5547) = Rs 79507

Therefore, Manoj will get Rs 79507 on maturity.

**(7) Divakaran deposited a sum of Rs 6250 in the Allaha bad bank for 1 year, compounded half-yearly at 8% per annum. Find the compound interest he gets.**

Solution: Rate of interest = 8% per annum = 4% for half year

Time = 1 year = 2 half year

Original principle = Rs 6250.

Principle for the first half year = Rs 6250

Amount at the end of the second half year = Rs (6500 + 260) = Rs 6760

∴ Compound interest = Rs (6760 – 6250) = Rs 510

Hence, Divankaran gets the compound interest of Rs 510.

**(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?**

Solution: Rate of interest = 10% per annum = 5% for half year

Time = 1 (1/2) years = 3 half years

Original principle = Rs 16000

Amount at the end of the third half year = Rs (17640 + 882)= Rs 18522

Therefore, The amount of money Michael has debt after 1(1/2) years is Rs 18522.

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