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Simple Interest examples ( Enter your problem )
 

1. Examples

Problem : 1 / 13 [ Simple Interest ]       Enter your problem
1. Find the simple interest on Rs 730 for 184 days at 25/4 % per annum.
Solution: Here `P = `Rs `730, R = 25/4` % and Time `= 184` days = `184/365` years

`SI = (P*R*N)/100 = ( 730 * 25/4 * 184 /365) / 100 = 23`

Simple Interest is Rs `23` .


Problem : 2 / 13 [ Simple Interest ]       Enter your problem
2. Find the simple interest on Rs 4660 for 5 years at 7/2 % per annum.
Solution: Here `P = ` Rs `4660, N = 5` years and `R = 7/2` %

`SI = (P*R*N)/100 = ( 4660 * 7/2 * 5 ) / 100 = 815.5`

Simple Interest is Rs `815.5` .


Problem : 3 / 13 [ Simple Interest ]       Enter your problem
3. The interest on a certain amount of money at 8 % per year for a period of 4 years is Rs 512 . Find the sum of money.
Solution: Here `SI = `Rs `512, N = 4` years, `R = 8` %

`SI = (P*R*N)/100`

`P = (SI*100) / (R*N)`

`P = (512 * 100 ) / ( 8 * 4 ) = 1600`

The sum of money is Rs `1600` .


Problem : 4 / 13 [ Simple Interest ]       Enter your problem
4. Simple Interest on Rs 972 at 14 % per annum for a certain time is Rs 476.28 . Find the time ?
Solution: Here `P = 972, SI = `Rs `476.28, R = 14`%

`SI = (P*R*N)/100 `

`N = (SI*100) / (P*R)`

`N = ( 476.28 * 100 ) / ( 972 * 14 ) = 3.5`

The time is `3.5` years


Problem : 5 / 13 [ Simple Interest ]       Enter your problem
5. Simple Interest on Rs 972 at a certain rate % per annum for 3.5 years is Rs 476.28 . Find the rate ?
Solution: Here `P = 972, SI = ` Rs `476.28, N = 3.5`

`SI = (P*R*N)/100`

`R = (SI*100) / (P*N) = ( 476.28 * 100 ) / ( 972 * 3.5 ) = 14`

The rate is `14` %.


Problem : 6 / 13 [ Simple Interest ]       Enter your problem
6. A sum of money lent at simple interest amounts to Rs 1008 in 2 years and to 1112 in 3 years.Find the sum and the rate of interest.
Solution: Principal + Interest for `3` years = `1112`

Principal + Interest for `2` years = `1008`

`=>` Interest for `1` year = `1112 - 1008 = 104`

`=>` Interest for `2` years = `2 * 104 = 208`

Now, Principal + Interest for `2` years = `1008`

`=>` Principal + `208 = 1008`

`=>` Principal = `1008 - 208 = 800`

`SI = (P*R*N)/100`

`R = (SI*100) / (P*N) = ( 208 * 100 ) / ( 800 * 2 ) = 13`

The Sum of money is Rs `800` and the rate of interest is `13` %


Problem : 7 / 13 [ Simple Interest ]       Enter your problem
7. What sum of money lent out at simple interest at 9 % p.a. for 3/2 years will produce the same interest as Rs 2250 lent at 6 % p.a. for 5 years.
Solution: Here `P = ` Rs `2250, N = 5` years, `R = 6`%

`SI = (P*R*N)/100`

`SI = (2250 * 6 * 5 ) / 100 = 675`

Now, `SI = ` Rs `675, N = 3/2` years, `R = 9`%

`SI = (P*R*N)/100`

`P = (SI * 100) / (R * N) = ( 675 * 100) / ( 9 * 3/2 ) = 5000`

The sum of money is Rs `5000`


Problem : 8 / 13 [ Simple Interest ]       Enter your problem
8. A man puts out Rs 500 for 4 years on simple interest and Rs 600 for 3 years. The total interest he receives is Rs 190 . What is the rate percent per annum?
Solution: Let the rate(`R`) % per annum = `X`

`SI` on Rs `500 = (P*R*N)/100 = (500 * X * 4) / 100 = 20 X`

`SI` on Rs `600 = (P*R*N)/100 = (600 * X * 3) / 100 = 18 X`

Total `SI` = Rs `190`

`20 X + 18 X = 190`

`38 X = 190`

`X = 190 / 38 = 5`

Rate is `5` %


Problem : 9 / 13 [ Simple Interest ]       Enter your problem
9. A sum was put at simple interest at a certain rate for 2 years. Had it been put at 3 % higher rate, it whould have fetched Rs 300 more. Find the sum.
Solution: Let sum = Rs `X` and original rate = `R` %

Then,
`(X * ( R + 3 ) * 2)/100 - (X * R * 2)/100 = 300`

`2 R X + 6 X - 2 R X = 300 * 100`

`6 X = 300 * 100`

`X = 5000`

The sum is Rs `5000` .


Problem : 10 / 13 [ Simple Interest ]       Enter your problem
10. Divide Rs 16875 into two parts such that the interest at 7/2 % p.a. for 2 years on one part is equal to the other at 4 % p.a. for 5 years.
Solution: Let the Principal of one part = `X` Rs

The Principal of second part = `( 16875 - X )` Rs

For one part, `P = X` Rs, `R = 7/2 %, N = 2` years

`SI = (P*R*N)/100`

`SI = ( X * 7/2 * 2 ) / 100 = (7 * X)/100 ->(1)`

Now for second part, `P = ( 16875 - X ) Rs, R = 4 %, N = 5` years

`SI = (P*R*N)/100`

`SI = (( 16875 - X ) * 4 * 5 ) / 100 = (20 * ( 16875 - X ))/100 ->(2)`

Interest is the same as `(1) = (2)`

`=> (7 * X)/100 = (20 * ( 16875 - X ))/100`

`=> 7 X = 20 * ( 16875 - X )`

`=> 7 X = 20 * 16875 - 20 X`

`=> 27 X = 20 * 16875`

`=> X = (20 * 16875) / 27`

`=> X = 12500`

`:.`One part of Principal = Rs `12500` and the second part = Rs `( 16875 - 12500 )` = Rs `4375`

The two parts are Rs `12500` and Rs `4375` .


Problem : 11 / 13 [ Simple Interest ]       Enter your problem
11. A shopkeeper borrowed Rs 20000 from two money lendeRs For one loan he paid 12 % and for the other 14 % per annum. After 1 year, he paid Rs 2560 as interest. How much did he borrow at each rate ?
Solution: Let money at `12 % = X` and that at `14 % = ( 20000 - X )`

After one year total interest = `2560`

`(X * 12 * 1) / 100 + ((20000 - X) * 14 * 1) / 100 = 2560`

`12 X + 14 * 20000 - 14 X = 2560 * 100`

`-2 X = -24000`

`X = 12000`

`:.`Money at `12` % = Rs `12000` and Money at `14` % = Rs `8000` .


Problem : 12 / 13 [ Simple Interest ]       Enter your problem
12. At what rate percent per annum will sum of money double in 8 years?
Solution: Let, Sum = `X`, Time = `8` years and Amount = `2X`.

`:. SI = X. `

`SI = (P*R*N)/100`

`R = (SI * 100)/(P * N) = (X * 100)/( X * 8 ) = 25/2` %

`:.` sum of money double at `25/2` % in `8` years.


Problem : 13 / 13 [ Simple Interest ]       Enter your problem
13. Rajeev deposited money in the post office which is doubled in 20 years at a simple rate of interest. In how many years will the original sum triple itself ?
Solution: Let, Sum = `X`, Time = `20` years and Amount = `2X`.

`:. SI = X. `

`SI = (P*R*N)/100`

`R = (SI * 100)/(P * N) = (X * 100)/( X * 20 ) = 5` %

`:.` sum of money double at `5` % in `20` years.






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