Simple Interest Sample Questions And Answers

Simple Interest Sample Questions And Answers


  • Posted by  Ragu 
    29 Jan, 2012

    Ex. 1. Find the simple interest on Rs. 68,000 at 16 2/3% per annum for 9 months.


    Sol. P = Rs.68000,R = 50/3% p.a and T = 9/12 years = 3/4years.

    ∴ S.I. = (P*R*T)/100 = Rs.(68,000*(50/3)*(3/4)*(1/100))= Rs.8500

    Ex. 2. Find the simple interest on Rs. 3000 at 6 1/4% per annum for the period from
    4th Feb., 2005 to 18th April, 2005.

    Sol. Time = (24+31+18)days = 73 days = 73/365 years = 1/5 years.

    P = Rs.3000 and R = 6 ¼ %p.a = 25/4%p.a
    ∴S.I. = Rs.(3,000*(25/4)*(1/5)*(1/100))= Rs.37.50.

    Remark : The day on which money is deposited is not counted while the day on which money is withdrawn is counted .

    Ex. 3. A sum at simple interests at 13 ½ % per annum amounts to Rs.2502.50 after 4 years find the sum.

    Sol. Let sum be Rs. x then , S.I.=Rs.(x*(27/2) *4*(1/100) ) = Rs.27x/50
    ∴amount = (Rs. x+(27x/50)) = Rs.77x/50
    ∴ 77x/50 = 2502.50 ⇔ x = (2502.50 * 50)/77 = 1625

    Hence , sum = Rs.1625.

    Ex. 4. A sum of Rs. 800 amounts to Rs. 920 in 8 years at simple intere
    interest rate is increased by 8%, it would amount to bow mucb ?
    Sol. S.l. = Rs. (920 - 800) = Rs. 120; p = Rs. 800, T = 3 yrs.
    R = ((100 x 120)/(800*3) ) % = 5%.
    New rate = (5 + 3)% = 8%.
    New S.l. = Rs. (800*8*3)/100 = Rs. 192.
    New amount = Rs.(800+192) = Rs. 992.

    Ex. 5. Adam borrowed some money at the rate of 6% p.a. for the first two years , at the rate of 9% p.a. for the next three years , and at the rate of 14% p.a. for the period beyond five years. if he pays a total interest of Rs. 11, 400 at the end of nine years how much money did he borrow ?

    Sol. Let the sum borrowed be x. Then,

    (x*2*6)/100 + (x*9*3)/100 + (x*14*4)/100 = 11400
    ⇔ (3x/25 + 27x/100 + 14x / 25) = 11400 ⇔ 95x/100 = 11400 ⇔ x = (11400*100)/95 = 12000.

    Hence , sum borrowed = Rs.12,000.

    Ex. 6. A certain sum of money amounts to Rs. 1008 in 2 years and to Rs.1164 in 3 ½ years. Find the sum and rate of interests.

    Sol.. S.I. for 1 ½ years = Rs.(1164-1008) = Rs.156.
    S.l. for 2 years = Rs.(156*(2/3)*2)=Rs.208

    Principal = Rs. (1008 - 208) = Rs. 800.

    Now, P = 800, T = 2 and S.l. = 208.

    Rate =(100* 208)/(800*2)% = 13%

    Ex. 7. At what rate percent per annum will a sum of money double in 16 years.

    Sol.. Let principal = P. Then, S.l. = P and T = 16 yrs.

    ∴Rate = (100 x P)/(P*16)% = 6 ¼ % p.a.

    Ex. 8. The simple interest on a sum of money is 4/9 of the principal .Find the rate percent and time, if both are numerically equal.

    Sol. Let sum = Rs. x. Then, S.l. = Rs. 4x/9

    Let rate = R% and time = R years.

    Then, (x*R*R)/100=4x/9 or R2 =400/9 or R = 20/3 = 6 2/3.

    ∴Rate = 6 2/3 % and Time = 6 2/3 years = 6 years 8 months.

    Ex. 9. The simple interest on a certain sum of money for 2 l/2 years at 12% per
    annum is Rs. 40 less tban the simple interest on the same sum for 3 1/2 years at 10% per annum. Find the sum.

    Sol. Let the sum be Rs. x Then, ((x*10*7)/(100*2)) ?? ( (x*12*5)/(100*2)) = 40
    ⇔ (7x/20)-(3x/10)=40
    ⇔ x = (40 * 20) = 800.

    Hence, the sum is Rs. 800.

    Ex. 10. A sum was put at simple interest at a certain rate for 3 years. Had it been
    put at 2% higher rate, it would have fetched Rs. 360 more. Find the sum.

    Sol. Let sum = P and original rate = R.
    Then, [ (P*(R+2)*3)/100] - [ (P*R*3)/100] = 360.

    ⇔ 3PR + 6P - 3PR = 36000 ⇔ 6P=36000 ⇔ P=6000

    Hence, sum = Rs. 6000.

    Ex. 11. What annual instalment will discharge a debt of Rs. 1092 due in 3 years
    at 12% simple interest?
    Sol . Let each Instalment be Rs. x
    Then, ( x+ ((x*12*1)/100)) + (x+ ((x*12*2)/100) ) + x = 1092
    ⇔ ((28x/25) + (31x/25) + x) = 1092 ⇔ (28x+31x+25x)=(1092*25)
    ⇔ x= (1092*25)/84 = Rs.325.

    ∴ Each instalment = Rs. 325.

    Ex. 12. A sum of Rs. 1550 is lent out into two parts, one at 8% and another one at
    6%. If the total annual income is Rs. 106, find the money lent at each rate.

    Sol. Let the sum lent at 8% be Rs. x and that at 6% be Rs. (1550 - x).
    ⇔ ((x*8*1)/100) + ((1550-x)*6*1)/100=106
    ⇔ 8x + 9300 -6x=10600 ⇔ 2x = 1300 ⇔ x = 650.
    ∴ Money lent at 8% = Rs. 650. Money lent at 6% = Rs. (1550 - 650) = Rs. 900.


  • 24 Sep, 2013

    In approximately how many years will a certain sum of money triple itself at 22% simple interest?

    Comments Received:
    Please give your suggestions and feedback:
  • 29 Jun, 2012

    At what rate percent per annum will a sum of money double in 16 years.

    Sol.. Let principal = P. Then, S.l. = P and T = 16 yrs.

    ∴Rate = (100 x P)/(P*16)% = 6 ¼ % p.a.

    i didnt get thz ansr. can anybody clarify my doubt

    Comments Received:
    Mahesh.: Hey, Its simple math formula Simple intrest = PTR/100 R = 100 * Simple Intrest / (PT) R = 100 * P / (P*16)
    Mrinmay: Simple interest(SI) = PTR/100 R = 100 * Simple Interest / Principal * Time So,Rate = 100 * P / (P*16)
    Please give your suggestions and feedback:
  • 29 Jun, 2012

    Ex. 3. A sum at simple interests at 13 ½ % per annum amounts to Rs.2502.50 after 4 years find the sum.

    Sol. Let sum be Rs. x then , S.I.=Rs.(x*(27/2) *4*(1/100) ) = Rs.27x/50
    ∴amount = (Rs. x+(27x/50)) = Rs.77x/50
    ∴ 77x/50 = 2502.50 ⇔ x = (2502.50 * 50)/77 = 1625

    Hence , sum = Rs.1625. how we will get 27x/50.plz clarify me

    Comments Received:
    Mahesh: Hey its very simple math calculation. x * (27/2) * 4 * (1/100) = (27x*4)/200 = 27x/50
    Please give your suggestions and feedback:

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