Compound Interest


  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


  1. If the difference between S.I. and C.I. for 2 years on a sum of money lent at 5% is ₹ 6, then
    the sum is









  1. View Hint View Answer Discuss in Forum

    Here , Difference = C.I. - S.I. = ₹ 6 , Time = 2 years , Rate = 5%
    We know that ,

    Difference =
    Pr2
    10000

    Correct Option: B

    Here , Difference = C.I. - S.I. = ₹ 6 , Time = 2 years , Rate = 5%
    We know that ,

    Difference =
    Pr2
    10000

    ⇒ 6 =
    P × 5 × 5
    10000

    ⇒  P = 6 × 400 = ₹ 2400



  1. The difference between the compound interest and simple interest on ₹ 10,000 for 2 years is ₹ 25. The rate of interest per annum is









  1. View Hint View Answer Discuss in Forum

    Here , Principal = ₹ 10000 , Difference = C.I. - S.I. = ₹ 25 , Time = 2 years , Rate = R%
    We can find required answer with the help of given formula ,

    Difference =
    PR2
    10000

    Correct Option: A

    Here , Principal = ₹ 10000 , Difference = C.I. - S.I. = ₹ 25 , Time = 2 years , Rate = R%
    We can find required answer with the help of given formula ,

    Difference =
    PR2
    10000

    ⇒ 25 =
    10000 × R2
    10000

    ⇒  R = 5%


  1. The difference between compound and simple interest on a certain sum for 3 years at 5% per annum is ₹ 122. The sum is









  1. View Hint View Answer Discuss in Forum

    Given Here , Difference = C.I. - S.I. = ₹ 122 , Time = 3 years , Rate = 5%
    Let the difference between CI and SI on a certain sum for 3 years at r % be y ,
    Using the given formula ,

    Sum =
    Difference × (100)3
    r2(300 + r)

    Sum =
    122 × 1003
    25(300 + 5)

    Correct Option: A

    Given Here , Difference = C.I. - S.I. = ₹ 122 , Time = 3 years , Rate = 5%
    Let the difference between CI and SI on a certain sum for 3 years at r % be y ,
    Using the given formula ,

    Sum =
    Difference × (100)3
    r2(300 + r)

    Sum =
    122 × 1003
    25(300 + 5)

    Sum =
    122000000
    = ₹ 16000
    25 × 305



  1. The difference between compound interest (compounded annually) and simple interest on a certain sum of money at 10% per annum for 2 years is ₹ 40. The sum is :









  1. View Hint View Answer Discuss in Forum

    Difference = C.I. - S.I. = ₹ 40 , Time = 2 years , Rate = 10%
    Let the principal be P.
    Using the given formula ,

    Compound interest = P 1 +
    R
    t − 1
    100

    C.I. = P 1 +
    10
    2 − 1
    100

    C.I. = P [(1.1)2 – 1]
    C.I. = P (1.21 – 1) = 0.21P
    SI =
    P × 2 × 10
    =
    P
    = 0.2P
    100 5

    According to the question,
    C.I. - S.I. = 40
    0.21P – 0.2P = 40
    ⇒  0.01P = 40
    ⇒  P =
    40
    = ₹ 4000
    0.01

    We can find required answer with the help of given formula :
    Here, C.I. – S.I. = ₹ 40 , R = 10% , T = 2 years, P = ?

    Correct Option: A

    Difference = C.I. - S.I. = ₹ 40 , Time = 2 years , Rate = 10%
    Let the principal be P.
    Using the given formula ,

    Compound interest = P 1 +
    R
    t − 1
    100

    C.I. = P 1 +
    10
    2 − 1
    100

    C.I. = P [(1.1)2 – 1]
    C.I. = P (1.21 – 1) = 0.21P
    SI =
    P × 2 × 10
    =
    P
    = 0.2P
    100 5

    According to the question,
    C.I. - S.I. = 40
    0.21P – 0.2P = 40
    ⇒  0.01P = 40
    ⇒  P =
    40
    = ₹ 4000
    0.01

    We can find required answer with the help of given formula :
    Here, C.I. – S.I. = ₹ 40 , R = 10% , T = 2 years, P = ?
    C.I. − S.I. = P
    R
    2
    100

    40 = P
    10
    2
    100

    P = ₹ 4000