Page 1
RD Sharma Solutions for Class 8 Maths Chapter 14 –
Compound Interest
EXERCISE 14.1 PAGE NO: 14.4
1. Find the compound interest when principal = Rs 3000, rate = 5% per annum and
time = 2 years.
Solution:
Given details are,
Principal (p) = Rs 3000
Rate (r) = 5%
Time = 2years
Interest for the first year = (3000×5×1)/100 = 150
Amount at the end of first year = Rs 3000 + 300 = Rs 3150
Principal interest for the second year = (3150×5×1)/100 = 157.5
Amount at the end of second year = Rs 3150 + 157.5 = Rs 3307.5
? Compound Interest = Rs 3307.5 – Rs 3000 = Rs 307.5
2. What will be the compound interest on Rs. 4000 in two years when rate of
interest is 5% per annum?
Solution:
Given details are,
Principal (p) = Rs 4000
Rate (r) = 5%
Time = 2years
By using the formula,
A = P (1 + R/100)
n
= 4000 (1 + 5/100)
2
= 4000 (105/100)
2
= Rs 4410
? Compound Interest = A – P = Rs 4410 – Rs 4000 = Rs 410
3. Rohit deposited Rs. 8000 with a finance company for 3 years at an interest of 15%
per annum. What is the compound interest that Rohit gets after 3 years?
Solution:
Given details are,
Principal (p) = Rs 8000
Rate (r) = 15%
Time = 3years
By using the formula,
A = P (1 + R/100)
n
= 8000 (1 + 15/100)
3
Page 2
RD Sharma Solutions for Class 8 Maths Chapter 14 –
Compound Interest
EXERCISE 14.1 PAGE NO: 14.4
1. Find the compound interest when principal = Rs 3000, rate = 5% per annum and
time = 2 years.
Solution:
Given details are,
Principal (p) = Rs 3000
Rate (r) = 5%
Time = 2years
Interest for the first year = (3000×5×1)/100 = 150
Amount at the end of first year = Rs 3000 + 300 = Rs 3150
Principal interest for the second year = (3150×5×1)/100 = 157.5
Amount at the end of second year = Rs 3150 + 157.5 = Rs 3307.5
? Compound Interest = Rs 3307.5 – Rs 3000 = Rs 307.5
2. What will be the compound interest on Rs. 4000 in two years when rate of
interest is 5% per annum?
Solution:
Given details are,
Principal (p) = Rs 4000
Rate (r) = 5%
Time = 2years
By using the formula,
A = P (1 + R/100)
n
= 4000 (1 + 5/100)
2
= 4000 (105/100)
2
= Rs 4410
? Compound Interest = A – P = Rs 4410 – Rs 4000 = Rs 410
3. Rohit deposited Rs. 8000 with a finance company for 3 years at an interest of 15%
per annum. What is the compound interest that Rohit gets after 3 years?
Solution:
Given details are,
Principal (p) = Rs 8000
Rate (r) = 15%
Time = 3years
By using the formula,
A = P (1 + R/100)
n
= 8000 (1 + 15/100)
3
RD Sharma Solutions for Class 8 Maths Chapter 14 –
Compound Interest
= 8000 (115/100)
3
= Rs 12167
? Compound Interest = A – P = Rs 12167 – Rs 8000 = Rs 4167
4. Find the compound interest on Rs. 1000 at the rate of 8% per annum for 1 ½
years when interest is compounded half yearly.
Solution:
Given details are,
Principal (p) = Rs 1000
Rate (r) = 8%
Time = 1 ½ years = 3/2 × 2 = 3 half years
By using the formula,
A = P (1 + R/200)
2n
= 1000 (1 + 8/200)
3
= 1000 (208/200)
3
= Rs 1124.86
? Compound Interest = A – P = Rs 1124.86 – Rs 1000 = Rs 124.86
5. Find the compound interest on Rs. 160000 for one year at the rate of 20% per
annum, if the interest is compounded quarterly.
Solution:
Given details are,
Principal (p) = Rs 160000
Rate (r) = 20% = 20/4 = 5% (for quarter year)
Time = 1year = 1 × 4 = 4 quarters
By using the formula,
A = P (1 + R/100)
n
= 160000 (1 + 5/100)
4
= 160000 (105/100)
4
= Rs 194481
? Compound Interest = A – P = Rs 194481 – Rs 160000 = Rs 34481
6. Swati took a loan of Rs. 16000 against her insurance policy at the rate of 12 ½ %
per annum. Calculate the total compound interest payable by Swati after 3 years.
Solution:
Given details are,
Principal (p) = Rs 16000
Rate (r) = 12 ½ % = 12.5%
Time = 3years
Page 3
RD Sharma Solutions for Class 8 Maths Chapter 14 –
Compound Interest
EXERCISE 14.1 PAGE NO: 14.4
1. Find the compound interest when principal = Rs 3000, rate = 5% per annum and
time = 2 years.
Solution:
Given details are,
Principal (p) = Rs 3000
Rate (r) = 5%
Time = 2years
Interest for the first year = (3000×5×1)/100 = 150
Amount at the end of first year = Rs 3000 + 300 = Rs 3150
Principal interest for the second year = (3150×5×1)/100 = 157.5
Amount at the end of second year = Rs 3150 + 157.5 = Rs 3307.5
? Compound Interest = Rs 3307.5 – Rs 3000 = Rs 307.5
2. What will be the compound interest on Rs. 4000 in two years when rate of
interest is 5% per annum?
Solution:
Given details are,
Principal (p) = Rs 4000
Rate (r) = 5%
Time = 2years
By using the formula,
A = P (1 + R/100)
n
= 4000 (1 + 5/100)
2
= 4000 (105/100)
2
= Rs 4410
? Compound Interest = A – P = Rs 4410 – Rs 4000 = Rs 410
3. Rohit deposited Rs. 8000 with a finance company for 3 years at an interest of 15%
per annum. What is the compound interest that Rohit gets after 3 years?
Solution:
Given details are,
Principal (p) = Rs 8000
Rate (r) = 15%
Time = 3years
By using the formula,
A = P (1 + R/100)
n
= 8000 (1 + 15/100)
3
RD Sharma Solutions for Class 8 Maths Chapter 14 –
Compound Interest
= 8000 (115/100)
3
= Rs 12167
? Compound Interest = A – P = Rs 12167 – Rs 8000 = Rs 4167
4. Find the compound interest on Rs. 1000 at the rate of 8% per annum for 1 ½
years when interest is compounded half yearly.
Solution:
Given details are,
Principal (p) = Rs 1000
Rate (r) = 8%
Time = 1 ½ years = 3/2 × 2 = 3 half years
By using the formula,
A = P (1 + R/200)
2n
= 1000 (1 + 8/200)
3
= 1000 (208/200)
3
= Rs 1124.86
? Compound Interest = A – P = Rs 1124.86 – Rs 1000 = Rs 124.86
5. Find the compound interest on Rs. 160000 for one year at the rate of 20% per
annum, if the interest is compounded quarterly.
Solution:
Given details are,
Principal (p) = Rs 160000
Rate (r) = 20% = 20/4 = 5% (for quarter year)
Time = 1year = 1 × 4 = 4 quarters
By using the formula,
A = P (1 + R/100)
n
= 160000 (1 + 5/100)
4
= 160000 (105/100)
4
= Rs 194481
? Compound Interest = A – P = Rs 194481 – Rs 160000 = Rs 34481
6. Swati took a loan of Rs. 16000 against her insurance policy at the rate of 12 ½ %
per annum. Calculate the total compound interest payable by Swati after 3 years.
Solution:
Given details are,
Principal (p) = Rs 16000
Rate (r) = 12 ½ % = 12.5%
Time = 3years
RD Sharma Solutions for Class 8 Maths Chapter 14 –
Compound Interest
By using the formula,
A = P (1 + R/100)
n
= 16000 (1 + 12.5/100)
3
= 16000 (112.5/100)
3
= Rs 22781.25
? Compound Interest = A – P = Rs 22781.25 – Rs 16000 = Rs 6781.25
7. Roma borrowed Rs. 64000 from a bank for 1 ½ years at the rate of 10% per
annum. Compare the total compound interest payable by Roma after 1 ½ years, if
the interest is compounded half-yearly.
Solution:
Given details are,
Principal (p) = Rs 64000
Rate (r) = 10 % = 10/2 % (for half a year)
Time = 1 ½ years = 3/2 × 2 = 3 (half year)
By using the formula,
A = P (1 + R/100)
n
= 64000 (1 + 10/2×100)
3
= 64000 (210/200)
3
= Rs 74088
? Compound Interest = A – P = Rs 74088 – Rs 64000 = Rs 10088
8. Mewa lal borrowed Rs. 20000 from his friend Rooplal at 18% per annum simple
interest. He lent it to Rampal at the same rate but compounded annually. Find his
gain after 2 years.
Solution:
Given details are,
Principal (p) = Rs 20000
Rate (r) = 18 %
Time = 2 years
By using the formula,
Interest amount Mewa lal has to pay,
By using the formula,
Simple interest = P×T×R/100
= (20000×18×2)/100 = 7200
Interest amount Rampal has to pay to Mewa lal,
By using the formula,
A = P (1 + R/100)
n
Page 4
RD Sharma Solutions for Class 8 Maths Chapter 14 –
Compound Interest
EXERCISE 14.1 PAGE NO: 14.4
1. Find the compound interest when principal = Rs 3000, rate = 5% per annum and
time = 2 years.
Solution:
Given details are,
Principal (p) = Rs 3000
Rate (r) = 5%
Time = 2years
Interest for the first year = (3000×5×1)/100 = 150
Amount at the end of first year = Rs 3000 + 300 = Rs 3150
Principal interest for the second year = (3150×5×1)/100 = 157.5
Amount at the end of second year = Rs 3150 + 157.5 = Rs 3307.5
? Compound Interest = Rs 3307.5 – Rs 3000 = Rs 307.5
2. What will be the compound interest on Rs. 4000 in two years when rate of
interest is 5% per annum?
Solution:
Given details are,
Principal (p) = Rs 4000
Rate (r) = 5%
Time = 2years
By using the formula,
A = P (1 + R/100)
n
= 4000 (1 + 5/100)
2
= 4000 (105/100)
2
= Rs 4410
? Compound Interest = A – P = Rs 4410 – Rs 4000 = Rs 410
3. Rohit deposited Rs. 8000 with a finance company for 3 years at an interest of 15%
per annum. What is the compound interest that Rohit gets after 3 years?
Solution:
Given details are,
Principal (p) = Rs 8000
Rate (r) = 15%
Time = 3years
By using the formula,
A = P (1 + R/100)
n
= 8000 (1 + 15/100)
3
RD Sharma Solutions for Class 8 Maths Chapter 14 –
Compound Interest
= 8000 (115/100)
3
= Rs 12167
? Compound Interest = A – P = Rs 12167 – Rs 8000 = Rs 4167
4. Find the compound interest on Rs. 1000 at the rate of 8% per annum for 1 ½
years when interest is compounded half yearly.
Solution:
Given details are,
Principal (p) = Rs 1000
Rate (r) = 8%
Time = 1 ½ years = 3/2 × 2 = 3 half years
By using the formula,
A = P (1 + R/200)
2n
= 1000 (1 + 8/200)
3
= 1000 (208/200)
3
= Rs 1124.86
? Compound Interest = A – P = Rs 1124.86 – Rs 1000 = Rs 124.86
5. Find the compound interest on Rs. 160000 for one year at the rate of 20% per
annum, if the interest is compounded quarterly.
Solution:
Given details are,
Principal (p) = Rs 160000
Rate (r) = 20% = 20/4 = 5% (for quarter year)
Time = 1year = 1 × 4 = 4 quarters
By using the formula,
A = P (1 + R/100)
n
= 160000 (1 + 5/100)
4
= 160000 (105/100)
4
= Rs 194481
? Compound Interest = A – P = Rs 194481 – Rs 160000 = Rs 34481
6. Swati took a loan of Rs. 16000 against her insurance policy at the rate of 12 ½ %
per annum. Calculate the total compound interest payable by Swati after 3 years.
Solution:
Given details are,
Principal (p) = Rs 16000
Rate (r) = 12 ½ % = 12.5%
Time = 3years
RD Sharma Solutions for Class 8 Maths Chapter 14 –
Compound Interest
By using the formula,
A = P (1 + R/100)
n
= 16000 (1 + 12.5/100)
3
= 16000 (112.5/100)
3
= Rs 22781.25
? Compound Interest = A – P = Rs 22781.25 – Rs 16000 = Rs 6781.25
7. Roma borrowed Rs. 64000 from a bank for 1 ½ years at the rate of 10% per
annum. Compare the total compound interest payable by Roma after 1 ½ years, if
the interest is compounded half-yearly.
Solution:
Given details are,
Principal (p) = Rs 64000
Rate (r) = 10 % = 10/2 % (for half a year)
Time = 1 ½ years = 3/2 × 2 = 3 (half year)
By using the formula,
A = P (1 + R/100)
n
= 64000 (1 + 10/2×100)
3
= 64000 (210/200)
3
= Rs 74088
? Compound Interest = A – P = Rs 74088 – Rs 64000 = Rs 10088
8. Mewa lal borrowed Rs. 20000 from his friend Rooplal at 18% per annum simple
interest. He lent it to Rampal at the same rate but compounded annually. Find his
gain after 2 years.
Solution:
Given details are,
Principal (p) = Rs 20000
Rate (r) = 18 %
Time = 2 years
By using the formula,
Interest amount Mewa lal has to pay,
By using the formula,
Simple interest = P×T×R/100
= (20000×18×2)/100 = 7200
Interest amount Rampal has to pay to Mewa lal,
By using the formula,
A = P (1 + R/100)
n
RD Sharma Solutions for Class 8 Maths Chapter 14 –
Compound Interest
= 20000 (1 + 18/100)
2
= 20000 (118/100)
2
= Rs 27848 – 20000 (principal amount)
= Rs 7848
? Mewa lal gain = Rs (7848 - 7200) = Rs 648
9. Find the compound interest on Rs. 8000 for 9 months at 20% per annum
compounded quarterly.
Solution:
Given details are,
Principal (p) = Rs 8000
Rate (r) = 20 % = 20/4 = 5% (for quarterly)
Time = 9 months = 9/3 = 3 (for quarter year)
By using the formula,
A = P (1 + R/100)
n
= 8000 (1 + 5/100)
3
= 8000 (105/100)
3
= Rs 9261
? Compound Interest = A – P = Rs 9261 – Rs 8000 = Rs 1261
10. Find the compound interest at the rate of 10% per annum for two years on that
principal which in two years at the rate of 10% per annum given Rs. 200 as simple
interest.
Solution:
Given details are,
Simple interest (SI) = Rs 200
Rate (r) = 10 %
Time = 2 years
So, by using the formula,
Simple interest = P×T×R/100
P = (SI × 100)/ T×R
= (200 × 100) / 2 × 10
= 20000/20
= Rs 1000
Now,
Rate of compound interest = 10%
Time = 2years
Page 5
RD Sharma Solutions for Class 8 Maths Chapter 14 –
Compound Interest
EXERCISE 14.1 PAGE NO: 14.4
1. Find the compound interest when principal = Rs 3000, rate = 5% per annum and
time = 2 years.
Solution:
Given details are,
Principal (p) = Rs 3000
Rate (r) = 5%
Time = 2years
Interest for the first year = (3000×5×1)/100 = 150
Amount at the end of first year = Rs 3000 + 300 = Rs 3150
Principal interest for the second year = (3150×5×1)/100 = 157.5
Amount at the end of second year = Rs 3150 + 157.5 = Rs 3307.5
? Compound Interest = Rs 3307.5 – Rs 3000 = Rs 307.5
2. What will be the compound interest on Rs. 4000 in two years when rate of
interest is 5% per annum?
Solution:
Given details are,
Principal (p) = Rs 4000
Rate (r) = 5%
Time = 2years
By using the formula,
A = P (1 + R/100)
n
= 4000 (1 + 5/100)
2
= 4000 (105/100)
2
= Rs 4410
? Compound Interest = A – P = Rs 4410 – Rs 4000 = Rs 410
3. Rohit deposited Rs. 8000 with a finance company for 3 years at an interest of 15%
per annum. What is the compound interest that Rohit gets after 3 years?
Solution:
Given details are,
Principal (p) = Rs 8000
Rate (r) = 15%
Time = 3years
By using the formula,
A = P (1 + R/100)
n
= 8000 (1 + 15/100)
3
RD Sharma Solutions for Class 8 Maths Chapter 14 –
Compound Interest
= 8000 (115/100)
3
= Rs 12167
? Compound Interest = A – P = Rs 12167 – Rs 8000 = Rs 4167
4. Find the compound interest on Rs. 1000 at the rate of 8% per annum for 1 ½
years when interest is compounded half yearly.
Solution:
Given details are,
Principal (p) = Rs 1000
Rate (r) = 8%
Time = 1 ½ years = 3/2 × 2 = 3 half years
By using the formula,
A = P (1 + R/200)
2n
= 1000 (1 + 8/200)
3
= 1000 (208/200)
3
= Rs 1124.86
? Compound Interest = A – P = Rs 1124.86 – Rs 1000 = Rs 124.86
5. Find the compound interest on Rs. 160000 for one year at the rate of 20% per
annum, if the interest is compounded quarterly.
Solution:
Given details are,
Principal (p) = Rs 160000
Rate (r) = 20% = 20/4 = 5% (for quarter year)
Time = 1year = 1 × 4 = 4 quarters
By using the formula,
A = P (1 + R/100)
n
= 160000 (1 + 5/100)
4
= 160000 (105/100)
4
= Rs 194481
? Compound Interest = A – P = Rs 194481 – Rs 160000 = Rs 34481
6. Swati took a loan of Rs. 16000 against her insurance policy at the rate of 12 ½ %
per annum. Calculate the total compound interest payable by Swati after 3 years.
Solution:
Given details are,
Principal (p) = Rs 16000
Rate (r) = 12 ½ % = 12.5%
Time = 3years
RD Sharma Solutions for Class 8 Maths Chapter 14 –
Compound Interest
By using the formula,
A = P (1 + R/100)
n
= 16000 (1 + 12.5/100)
3
= 16000 (112.5/100)
3
= Rs 22781.25
? Compound Interest = A – P = Rs 22781.25 – Rs 16000 = Rs 6781.25
7. Roma borrowed Rs. 64000 from a bank for 1 ½ years at the rate of 10% per
annum. Compare the total compound interest payable by Roma after 1 ½ years, if
the interest is compounded half-yearly.
Solution:
Given details are,
Principal (p) = Rs 64000
Rate (r) = 10 % = 10/2 % (for half a year)
Time = 1 ½ years = 3/2 × 2 = 3 (half year)
By using the formula,
A = P (1 + R/100)
n
= 64000 (1 + 10/2×100)
3
= 64000 (210/200)
3
= Rs 74088
? Compound Interest = A – P = Rs 74088 – Rs 64000 = Rs 10088
8. Mewa lal borrowed Rs. 20000 from his friend Rooplal at 18% per annum simple
interest. He lent it to Rampal at the same rate but compounded annually. Find his
gain after 2 years.
Solution:
Given details are,
Principal (p) = Rs 20000
Rate (r) = 18 %
Time = 2 years
By using the formula,
Interest amount Mewa lal has to pay,
By using the formula,
Simple interest = P×T×R/100
= (20000×18×2)/100 = 7200
Interest amount Rampal has to pay to Mewa lal,
By using the formula,
A = P (1 + R/100)
n
RD Sharma Solutions for Class 8 Maths Chapter 14 –
Compound Interest
= 20000 (1 + 18/100)
2
= 20000 (118/100)
2
= Rs 27848 – 20000 (principal amount)
= Rs 7848
? Mewa lal gain = Rs (7848 - 7200) = Rs 648
9. Find the compound interest on Rs. 8000 for 9 months at 20% per annum
compounded quarterly.
Solution:
Given details are,
Principal (p) = Rs 8000
Rate (r) = 20 % = 20/4 = 5% (for quarterly)
Time = 9 months = 9/3 = 3 (for quarter year)
By using the formula,
A = P (1 + R/100)
n
= 8000 (1 + 5/100)
3
= 8000 (105/100)
3
= Rs 9261
? Compound Interest = A – P = Rs 9261 – Rs 8000 = Rs 1261
10. Find the compound interest at the rate of 10% per annum for two years on that
principal which in two years at the rate of 10% per annum given Rs. 200 as simple
interest.
Solution:
Given details are,
Simple interest (SI) = Rs 200
Rate (r) = 10 %
Time = 2 years
So, by using the formula,
Simple interest = P×T×R/100
P = (SI × 100)/ T×R
= (200 × 100) / 2 × 10
= 20000/20
= Rs 1000
Now,
Rate of compound interest = 10%
Time = 2years
RD Sharma Solutions for Class 8 Maths Chapter 14 –
Compound Interest
By using the formula,
A = P (1 + R/100)
n
= 1000 (1 + 10/100)
2
= 1000 (110/100)
2
= Rs 1210
? Compound Interest = A – P = Rs 1210 – Rs 1000 = Rs 210
11. Find the compound interest on Rs. 64000 for 1 year at the rate of 10% per
annum compounded quarterly.
Solution:
Given details are,
Principal (p) = Rs 64000
Rate (r) = 10 % = 10/4 % (for quarterly)
Time = 1year = 1× 4 = 4 (for quarter in a year)
By using the formula,
A = P (1 + R/100)
n
= 64000 (1 + 10/4×100)
4
= 64000 (410/400)
4
= Rs 70644.03
? Compound Interest = A – P = Rs 70644.03 – Rs 64000 = Rs 6644.03
12. Ramesh deposited Rs. 7500 in a bank which pays him 12% interest per annum
compounded quarterly. What is the amount which he receives after 9 months.
Solution:
Given details are,
Principal (p) = Rs 7500
Rate (r) = 12 % = 12/4 = 3 % (for quarterly)
Time = 9 months = 9/12years = 9/12 × 4 = 3 (for quarter in a year)
By using the formula,
A = P (1 + R/100)
n
= 7500 (1 + 3/100)
3
= 7500 (103/100)
3
= Rs 8195.45
? Required amount is Rs 8195.45
13. Anil borrowed a sum of Rs. 9600 to install a hand pump in his dairy. If the rate
of interest is 5 ½ % per annum compounded annually, determine the compound
interest which Anil will have to pay after 3 years.
Solution:
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