Simple interest
- In a certain time, the ratio of a certain principal and the simple interest obtained from it are in the ratio 10 : 3 at 10% interest per annum. The number of years the money was invested is
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We can find the the required answer with the help of given formula ,
Time = Interest × 100 Principal × Rate Time = 3 × 100 10 10 Correct Option: B
We can find the the required answer with the help of given formula ,
Time = Interest × 100 Principal × Rate Time = 3 × 100 = 3 Years. 10 10
- With a given rate of simple inerest, the ratio of principal and amount for a certain period of time is 4 : 5. After 3 years, with the same rate of interest, the ratio of the principal and amount becomes 5 : 7. The rate of interest is
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Case-I,
Let Principal be 4p and Amount be 5p .
Simple Interest = Amount - Principal = 5p – 4p = p
We know that ,SI = P × R × T 100 ∴ p = 4p × R × T 100 ⇒ T = 25 Years. R
Case-II,
Let Principal be 5q and Amount be 7q .T = 25 + 3 = 
25 + 3R 
Years. R R
Simple Interest = Amount - Principal = 7q – 5q = 2q∴ 2q = 5q × R × (25 + 3R) R × 100
Correct Option: C
Case-I,
Let Principal be 4p and Amount be 5p .
Simple Interest = Amount - Principal = 5p – 4p = p
We know that ,SI = P × R × T 100 ∴ p = 4p × R × T 100 ⇒ T = 25 Years. R
Case-II,
Let Principal be 5q and Amount be 7q .T = 25 + 3 = 25 + 3R Years. R R
Simple Interest = Amount - Principal = 7q – 5q = 2q∴ 2q = 5q × R × (25 + 3R) R × 100
⇒ 40 = 25 + 3R
⇒ 3R = 40 – 25 = 15 %⇒ R = 15 = 5% 3
- A person invests money in three different schemes for 6 years, 10 years and 12 years at 10 percent, 12 percent and 15 percent simple interest respectively. At the completion of each scheme, he gets the same interest. The ratio of his investment is
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We can find the required answer with the help of given formula ,
P1 : P2 : P3 = 1 : 1 : 1 r1t1 r2t2 r3t3 P1 : P2 : P3 = 1 : 1 : 1 6 × 10 10 × 12 12 × 15
Correct Option: A
We can find the required answer with the help of given formula ,
P1 : P2 : P3 = 1 : 1 : 1 r1t1 r2t2 r3t3 P1 : P2 : P3 = 1 : 1 : 1 6 × 10 10 × 12 12 × 15 P1 : P2 : P3 = 1 : 1 : 1 60 120 180
P1 : P2 : P3 = 6 : 3 : 2
- A person lent 5,000 partly at the rate of 4 percent and partly at the rate of 5 percent per annum simple interest. The total interest after 2 years is 440. To find the sum of money lentat each of the above rates, 5,000 is to be divided in the ratio :
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Let the sum of p be lent at the rate of 4% and (5000 – p) at the rate of 5%
we know that ,SI = P × R × T 100
From question , we havep × 4 × 2 + (5000 - p) × 5 × 2 = 440 100 100
Correct Option: D
Let the sum of p be lent at the rate of 4% and (5000 – p) at the rate of 5%
we know that ,SI = P × R × T 100
From question , we havep × 4 × 2 + (5000 - p) × 5 × 2 = 440 100 100
⇒ 8p + 50000 – 10p = 44000
⇒ 2p = 50000 – 44000 = 6000
⇒ p = ₹ 3000
∴ (5000 – p) = (5000 – 3000) = 2000
Now, Required ratio = First part : second part = 3000 : 2000 = 3 : 2
- A sum of 1550 was lent partly at 5% and partly at 8% simple interest. The total interest received after 3 years is 300. The ratio of money lent at 5% to that at 8% is :
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Let the sum lent at the rate of interest 5% per annum is p and at the rate of interest 8% per annum is (1550 – p)
According to the question,p × 5 × 3 + (1500 - p) × 8 × 3 = 300 100 100 ⇒ 15p + 37200 - 24p = 300 100 100
Correct Option: D
Let the sum lent at the rate of interest 5% per annum is p and at the rate of interest 8% per annum is (1550 – p)
According to the question,p × 5 × 3 + (1500 - p) × 8 × 3 = 300 100 100 ⇒ 15p + 37200 - 24p = 300 100 100
⇒ 15p + 37200 – 24p = 300 × 100
⇒ 9p = ₹ 7200
∴ p = 800 and, 1550 – p = 1550 – 800 = ₹ 750
∴ Ratio of money lent at 5% to that at 8% = 800 : 750 = 16 : 15
