Compound Interest


  1. The difference between the compound interest and the simple interest on a certain sum at 5% per annum for 2 years is ₹ 1.50. The sum is









  1. View Hint View Answer Discuss in Forum

    Given that , Difference = C.I. - S.I. = ₹ 1.50 , Time = 2 years , Rate = 5%
    Using the given formula ,

    Difference =
    PR2
    10000

    Correct Option: A

    Given that , Difference = C.I. - S.I. = ₹ 1.50 , Time = 2 years , Rate = 5%
    Using the given formula ,

    Difference =
    PR2
    10000

    ⇒ 1.50 =
    P × 5 × 5
    (100)2

    ⇒  P = 400 × 1.5 = ₹ 600


  1. On a certain sum of money, the difference between the compound interest for a year, payable half-yearly, and the simple interest for a year is ₹ 180. If the rate of interest in both the cases is 10%, then the sum is









  1. View Hint View Answer Discuss in Forum

    If the interest is compounded half yearly,
    Time = 2 years , Rate = 5% half yearly
    Using the given formula ,

    C.I. = P 1 +
    R
    T − 1
    100

    C.I. = P 1 +
    5
    2 − 1
    100

    C.I. = P
    21
    2 − 1
    20

    C.I. =
    41P
    400

    S.I. =
    P × R × T
    100

    S.I. =
    P × 10
    =
    P
    10010

    According to question ,
    ∴ C.I. - S.I. = 180
    41P
    P
    = 180
    40010

    ⇒ 
    41 − 40P
    = 180
    400

    ⇒ 
    P
    = 180
    400

    ⇒  P = ₹ 72000
    Second Method to solve this question :
    Here, C.I. – S.I. = ₹ 180
    Interest is compounded half yearly ,
    R =
    10
    = 5%, T = 2 years
    5

    C.I. − S.I. = P
    R
    2
    100

    Correct Option: B

    If the interest is compounded half yearly,
    Time = 2 years , Rate = 5% half yearly
    Using the given formula ,

    C.I. = P 1 +
    R
    T − 1
    100

    C.I. = P 1 +
    5
    2 − 1
    100

    C.I. = P
    21
    2 − 1
    20

    C.I. =
    41P
    400

    S.I. =
    P × R × T
    100

    S.I. =
    P × 10
    =
    P
    10010

    According to question ,
    ∴ C.I. - S.I. = 180
    41P
    P
    = 180
    40010

    ⇒ 
    41 − 40P
    = 180
    400

    ⇒ 
    P
    = 180
    400

    ⇒  P = ₹ 72000
    Second Method to solve this question :
    Here, C.I. – S.I. = ₹ 180
    Interest is compounded half yearly ,
    R =
    10
    = 5%, T = 2 years
    5

    C.I. − S.I. = P
    R
    2
    100

    ⇒ 180 = P
    5
    2
    100

    ⇒  P = 180 × 20 × 20
    P = ₹ 72000



    1. The difference between simple and compound interests on a sum of money at 4% per annum for 2 years is ₹ 8. The sum is









    1. View Hint View Answer Discuss in Forum

      Here , Difference = C.I. - S.I. = ₹ 8 , Time = 2 years , Rate = 4%
      Let the sum be P.
      When difference between the compound interest and simple interest on a certain sum of money for 2 years at r% rate is y, then the sum is given by:

      Sum = Difference ×
      100
      2
      Rate

      Correct Option: D

      Here , Difference = C.I. - S.I. = ₹ 8 , Time = 2 years , Rate = 4%
      Let the sum be P.
      When difference between the compound interest and simple interest on a certain sum of money for 2 years at r% rate is y, then the sum is given by:

      Sum = Difference ×
      100
      2
      Rate

      Sum = ₹ 8 ×
      100
      2
      4

      Sum = ₹ 8 × 25 × 25 = ₹ 5000


    1. On what sum does the difference between the compound interest and the simple interest for 3 years at 10% is ₹ 31 ?









    1. View Hint View Answer Discuss in Forum

      Let the sum be P.
      R = 10% , T = 3 years
      Using the given formula ,

      S.I. =
      P × R × T
      100

      S.I. =
      P × 10 × 3
      =
      3
      P
      10010

      C.I. = 1 +
      R
      T − 1P
      100

      C.I. = 1 +
      10
      3 − 1P
      100

      C.I. =
      11
      3 − 1P
      10

      C.I. =
      1331
      − 1 P =
      331
      P
      10001000

      ∴ C.I. - S.I. = ₹ 31
      331
      P −
      3
      P = 31
      100010

      (331 − 300)
      P = 31
      1000

      31
      P = 31
      1000

      ⇒ P = 1000
      ∴  Sum = ₹ 1000
      We can find required answer with the help of given formula :
      Here, C.I. – S.I. = ₹ 31 , R = 10% , T = 3 years , P = ?
      C.I. − S.I. = P
      R
      2 × 3 +
      R
      100100

      Correct Option: D

      Let the sum be P.
      R = 10% , T = 3 years
      Using the given formula ,

      S.I. =
      P × R × T
      100

      S.I. =
      P × 10 × 3
      =
      3
      P
      10010

      C.I. = 1 +
      R
      T − 1P
      100

      C.I. = 1 +
      10
      3 − 1P
      100

      C.I. =
      11
      3 − 1P
      10

      C.I. =
      1331
      − 1 P =
      331
      P
      10001000

      ∴ C.I. - S.I. = ₹ 31
      331
      P −
      3
      P = 31
      100010

      (331 − 300)
      P = 31
      1000

      31
      P = 31
      1000

      ⇒ P = 1000
      ∴  Sum = ₹ 1000
      We can find required answer with the help of given formula :
      Here, C.I. – S.I. = ₹ 31 , R = 10% , T = 3 years , P = ?
      C.I. − S.I. = P
      R
      2 × 3 +
      R
      100100

      31 = P
      10
      2 × 3 +
      10
      100100

      31 = P ×
      1
      ×
      31
      10010

      P = ₹ 1000



    1. On a certain sum of money lent out at 16% p.a. the difference between the compound interest for 1 year, payable half yearly, and the simple interest for 1 year is ₹ 56. The sum is









    1. View Hint View Answer Discuss in Forum

      As per the given in question ,
      Rate of interest = 8% per half year , Time = 2 half years , Difference = C.I. - S.I. = ₹ 56

      ⇒  Difference of interests =
      PR2
      100

      ⇒  56 =
      P × (8)2
      (100)2

      Correct Option: C

      As per the given in question ,
      Rate of interest = 8% per half year , Time = 2 half years , Difference = C.I. - S.I. = ₹ 56

      ⇒  Difference of interests =
      PR2
      100

      ⇒  56 =
      P × (8)2
      (100)2

      ⇒  P =
      56 × 10000
      = ₹ 8750
      64