Simple interest


  1. An old article is available for ₹ 12,000 at cash payment or is available for ₹ 7,000 cash payment and a monthly instalment of ₹630 for 8 months. The rate per cent per annum is









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    As per the given in question , we have
    Simple Interest = (7000 + 630 × 8) – 12000
    Simple Interest = (7000 + 5040) – 12000
    Simple Interest = 12040 – 12000 = 40
    Total Principal = 5000 + 4370 + 3740 + 3110 + 2480 + 1850 + 1220 + 590 = ₹ 22360

    Correct Option: A

    As per the given in question , we have
    Simple Interest = (7000 + 630 × 8) – 12000
    Simple Interest = (7000 + 5040) – 12000
    Simple Interest = 12040 – 12000 = 40
    Total Principal = 5000 + 4370 + 3740 + 3110 + 2480 + 1850 + 1220 + 590 = ₹ 22360

    Rate =
    40 × 100 ×12
    ≈ 2.1%
    22360 × 1


  1. Ramesh deposited 15600 in a fixed deposit at the rate of 10% per annum simple interest. After every second year, he adds his interest earnings to the principal. The interest at the end of fourth year is









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    According to question ,

    SI earned after two years =
    15600 × 10 × 2
    = ₹ 3120
    100

    ∴ Principal for next two years = ₹ (15600 + 3120) = ₹ 18720

    Correct Option: D

    According to question ,

    SI earned after two years =
    15600 × 10 × 2
    = ₹ 3120
    100

    ∴ Principal for next two years = ₹ (15600 + 3120) = ₹ 18720
    SI earned at the end of fourth year =
    18720 × 10 × 1
    = ₹ 1872
    100



  1. A part of ₹ 1500 was lent at 10% per annum and the rest at 7% per annum simple interest. The total interest earned in three years was ₹ 396. The sum lent at 10% was









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    Let p be lent at 10% per annum.
    ∴ (1500 – p ) is lent at 7% per annum.

    Now,
    p × 10 × 3
    +
    (1500 - p) × 7 × 3
    = 396
    100 100

    Correct Option: A

    Let p be lent at 10% per annum.
    ∴ (1500 – p ) is lent at 7% per annum.

    Now,
    p × 10 × 3
    +
    (1500 - p) × 7 × 3
    = 396
    100 100

    ⇒ 30p + 31500 – 21p = 39600
    ⇒ 9p = 39600 – 31500
    ⇒ p = 8100 ÷ 9 = ₹ 900


  1. If A borrowed Rs. P at x% and B borrowed Rs. Q (> P) at y% per annum at simple interest at the same time, then the amount of their debts will be equal after









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    Let amounts be equal in T years.
    We can find the SI with the help of given formula ,

    S.I =
    Principal × Time × Rate
    100

    ∴ P +
    P × x × T
    = Q +
    Q × y × T
    100100

    PxT
    -
    QyT
    = Q - P
    100100

    ⇒ T
    Px - Qy
    Q - P
    100

    Correct Option: A

    Let amounts be equal in T years.
    We can find the SI with the help of given formula ,

    S.I =
    Principal × Time × Rate
    100

    ∴ P +
    P × x × T
    = Q +
    Q × y × T
    100100

    PxT
    -
    QyT
    = Q - P
    100100

    ⇒ T
    Px - Qy
    Q - P
    100

    ⇒ T = 100
    Q - P
    Px - Qy



  1. Mohan lends Rs. 500 to John and a certain sum to Tom at the same time at a simple interest of 8% per annum. If in 4 years, he altogether receives Rs. 210 as interest from the two, then the sum of money he lent to Tom was









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    Let the money lent to Tom be Rs. p.
    As we know that ,

    Simple interest =
    Principal × Time × Rate
    100

    500 × 8 × 4
    +
    p × 8 × 4
    = 210
    100 100

    ⇒ 160 +
    32p
    = 210
    100

    32p
    = 210 - 160 = 50
    100

    Correct Option: C

    Let the money lent to Tom be Rs. p.
    As we know that ,

    Simple interest =
    Principal × Time × Rate
    100

    500 × 8 × 4
    +
    p × 8 × 4
    = 210
    100 100

    ⇒ 160 +
    32p
    = 210
    100

    32p
    = 210 - 160 = 50
    100

    ⇒ p =
    50 × 100
    = Rs. 156.25
    32