Compound Interest
- If the difference between S.I. and C.I. for 2 years on a sum of money lent at 5% is ₹ 6, then
the sum is
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Here , Difference = C.I. - S.I. = ₹ 6 , Time = 2 years , Rate = 5%
We know that ,Difference = Pr2 10000
Correct Option: B
Here , Difference = C.I. - S.I. = ₹ 6 , Time = 2 years , Rate = 5%
We know that ,Difference = Pr2 10000 ⇒ 6 = P × 5 × 5 10000
⇒ P = 6 × 400 = ₹ 2400
- The difference between the compound interest and simple interest on ₹ 10,000 for 2 years is ₹ 25. The rate of interest per annum is
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Here , Principal = ₹ 10000 , Difference = C.I. - S.I. = ₹ 25 , Time = 2 years , Rate = R%
We can find required answer with the help of given formula ,Difference = PR2 10000
Correct Option: A
Here , Principal = ₹ 10000 , Difference = C.I. - S.I. = ₹ 25 , Time = 2 years , Rate = R%
We can find required answer with the help of given formula ,Difference = PR2 10000 ⇒ 25 = 10000 × R2 10000
⇒ R = 5%
- The difference between compound and simple interest on a certain sum for 3 years at 5% per annum is ₹ 122. The sum is
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Given Here , Difference = C.I. - S.I. = ₹ 122 , Time = 3 years , Rate = 5%
Let the difference between CI and SI on a certain sum for 3 years at r % be y ,
Using the given formula ,Sum = Difference × (100)3 r2(300 + r) Sum = 122 × 1003 25(300 + 5)
Correct Option: A
Given Here , Difference = C.I. - S.I. = ₹ 122 , Time = 3 years , Rate = 5%
Let the difference between CI and SI on a certain sum for 3 years at r % be y ,
Using the given formula ,Sum = Difference × (100)3 r2(300 + r) Sum = 122 × 1003 25(300 + 5) Sum = 122000000 = ₹ 16000 25 × 305
- The difference between compound interest (compounded annually) and simple interest on a certain sum of money at 10% per annum for 2 years is ₹ 40. The sum is :
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Difference = C.I. - S.I. = ₹ 40 , Time = 2 years , Rate = 10%
Let the principal be P.
Using the given formula ,Compound interest = P 
1 + R 
t − 1 
100 C.I. = P 1 + 10 2 − 1 100
C.I. = P [(1.1)2 – 1]
C.I. = P (1.21 – 1) = 0.21PSI = P × 2 × 10 = P = 0.2P 100 5
According to the question,
C.I. - S.I. = 40
0.21P – 0.2P = 40
⇒ 0.01P = 40⇒ P = 40 = ₹ 4000 0.01
We can find required answer with the help of given formula :
Here, C.I. – S.I. = ₹ 40 , R = 10% , T = 2 years, P = ?
Correct Option: A
Difference = C.I. - S.I. = ₹ 40 , Time = 2 years , Rate = 10%
Let the principal be P.
Using the given formula ,Compound interest = P 1 + R t − 1 100 C.I. = P 1 + 10 2 − 1 100
C.I. = P [(1.1)2 – 1]
C.I. = P (1.21 – 1) = 0.21PSI = P × 2 × 10 = P = 0.2P 100 5
According to the question,
C.I. - S.I. = 40
0.21P – 0.2P = 40
⇒ 0.01P = 40⇒ P = 40 = ₹ 4000 0.01
We can find required answer with the help of given formula :
Here, C.I. – S.I. = ₹ 40 , R = 10% , T = 2 years, P = ?C.I. − S.I. = P 
R 2 100 40 = P 10 2 100
P = ₹ 4000
- A sum of 6,000 is deposited for 3 years at 5% per annum compound interest (compounded
annually). The difference of interests for 3 and 2 years will be
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Here , Principal ( P ) = ₹ 6000 , Time = 3 years , Rate = 5%
Using the given formula ,C.I. = P 1 + R T − 1 100 C.I. after 3 years = 6000 1 + 5 3 − 1 100 = 6000 9261 − 8000 8000 = 6000 × 1261 = ₹ 945.75 8000
Again , Principal = ₹ 6000 , Time = 2 years , Rate = 5%
Correct Option: C
Here , Principal ( P ) = ₹ 6000 , Time = 3 years , Rate = 5%
Using the given formula ,C.I. = P 1 + R T − 1 100 C.I. after 3 years = 6000 1 + 5 3 − 1 100 = 6000 9261 − 8000 8000 = 6000 × 1261 = ₹ 945.75 8000
Again , Principal = ₹ 6000 , Time = 2 years , Rate = 5%CI after 2 years = 6000 1 + 5 2 − 1 100 = 6000 441 − 400 400 = 6000 × 41 = ₹ 615 400
∴ Required difference = CI after 3 years - CI after 2 years
Required difference = ₹ (945.75 – 615) = ₹ 330.75
