Compound Interest
- The compound interest on Rs. 12000 for 9 months at 20% per annum, interest being compounded quarterly is :
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Given that , P = Rs. 12000 , Rate of interest = 20 = 5% per quarter , Time = 3 quarters 4
We can find required answer with the help of given formula ,∴ C.I. = P 
1 + R 
T − 1 
100 C.I. = 12000 1 + 5 3 − 1 100 C.I. = 12000 1 + 1 3 − 1 20 C.I. = 12000 21 3 − 1 20 C.I. = 12000 
9261 − 1 8000
Correct Option: C
Given that , P = Rs. 12000 , Rate of interest = 20 = 5% per quarter , Time = 3 quarters 4
We can find required answer with the help of given formula ,∴ C.I. = P 1 + R T − 1 100 C.I. = 12000 1 + 5 3 − 1 100 C.I. = 12000 1 + 1 3 − 1 20 C.I. = 12000 21 3 − 1 20 C.I. = 12000 9261 − 1 8000 C.I. = 12000 9261 - 8000 8000 ∴ C.I. = 12000 × 1261 = Rs. 1891.5 8000
- A certain sum will amount to ₹ 12,100 in 2 years at 10% per annum of compound interest, interest being compounded annually. The sum is
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Given in question , Amount ( A ) = ₹ 12,100 , P = ? , Rate ( R ) = 10% , Time = 2 years
Using the given formula ,A = P 1 + R T 100 ⇒ 12100 = P 1 + 10 2 100 ⇒ 12100 = P 11 2 100 ⇒ 12100 = P × 121 100
Correct Option: D
Given in question , Amount ( A ) = ₹ 12,100 , P = ? , Rate ( R ) = 10% , Time = 2 years
Using the given formula ,A = P 1 + R T 100 ⇒ 12100 = P 1 + 10 2 100 ⇒ 12100 = P 11 2 100 ⇒ 12100 = P × 121 100 ⇒ P = 12100 × 100 = ₹ 10000 121
- In what time will Rs. 64,000 amount to Rs. 68,921 at 5% per annum, interest being compounded half yearly ?
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Interest is compounded half yearly ,
Here , Amount ( A ) = Rs. 68921 , P = Rs. 64,000Time = T half–years , Rate = 5 % per half year 2 A = P 1 + R T 100 ⇒ 68921 = 64000 1 + 5 T 200 ⇒ 68921 = 1 + 1 T 64000 40 ⇒ 68921 = 41 T 64000 40 ⇒ 41 3 = 41 T 40 40
Correct Option: D
Interest is compounded half yearly ,
Here , Amount ( A ) = Rs. 68921 , P = Rs. 64,000Time = T half–years , Rate = 5 % per half year 2 A = P 1 + R T 100 ⇒ 68921 = 64000 1 + 5 T 200 ⇒ 68921 = 1 + 1 T 64000 40 ⇒ 68921 = 41 T 64000 40 ⇒ 41 3 = 41 T 40 40
Equating powers on both sides , we get⇒ T = 3 half years = 3 = 1 1 years 2 2
- The principal that yields a compound interest of ₹
420 during the second year at 5% per annum is
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Given that , Compound Interest ( CI ) = ₹ 420 , P = ? , Rate ( R ) = 5%
Let the principal be Rs. P.
According to the question,P 1 + R 2 − P 1 + R = 420 100 100 P 1 + R . 1 + R − 1 = 420 100 100 ⇒ P 1 + R × R = 420 100 100 ⇒ P 1 + 5 × 5 = 420 100 100
Correct Option: C
Given that , Compound Interest ( CI ) = ₹ 420 , P = ? , Rate ( R ) = 5%
Let the principal be Rs. P.
According to the question,P 1 + R 2 − P 1 + R = 420 100 100 P 1 + R . 1 + R − 1 = 420 100 100 ⇒ P 1 + R × R = 420 100 100 ⇒ P 1 + 5 × 5 = 420 100 100 ⇒ P 1 + 1 = 420 × 20 20 ⇒ P × 21 = 420 × 20 20 ⇒ P = 420 × 20 × 20 = ₹ 8000 21
- On a certain principal the compound interest compounded annually for the second year at 10% per annum is ₹ 132. The principal is
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Let principal be Rs. P.
Here , Compound Interest ( CI ) = ₹ 132 , P = ? , Rate ( R ) = 10% , Time = 2 yearsInterest in 1 year = PRT 100 Interest in 1 year = P × 10 × 1 = ₹ P 100 10
According to question,∴ P 1 + R 2 − 1 − P = 132 100 10 ⇒ P 1 + 10 2 − 1 − P = 132 100 10 ⇒ P 11 2 − 1 − P = 132 10 10 ⇒ P 121 − 1 - P = 132 100 10 ⇒ P 121 - 100 - P = 132 100 10 ⇒ 21P − P = 132 100 10
Correct Option: C
Let principal be Rs. P.
Here , Compound Interest ( CI ) = ₹ 132 , P = ? , Rate ( R ) = 10% , Time = 2 yearsInterest in 1 year = PRT 100 Interest in 1 year = P × 10 × 1 = ₹ P 100 10
According to question,∴ P 1 + R 2 − 1 − P = 132 100 10 ⇒ P 1 + 10 2 − 1 − P = 132 100 10 ⇒ P 11 2 − 1 − P = 132 10 10 ⇒ P 121 − 1 - P = 132 100 10 ⇒ P 121 - 100 - P = 132 100 10 ⇒ 21P − P = 132 100 10 ⇒ 21P − 10P = 132 100 ⇒ 11P = 132 100 ⇒ P = 132 × 100 = ₹ 1200 11
