Ratio, Proportion


  1. ₹ 555 was to be divided among A, B and C in the ratio of
    1
    :
    1
    :
    1
    .
    456
    But by mistake it was divided in the ratio of 4 : 5 : 6. The amount in excess received by C was









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    Case I

    A : B : C =
    1
    :
    1
    :
    1
    456

    =
    1
    × 60 :
    1
    × 60 :
    1
    × 60
    456

    [ LCM of 4, 5 and 6 = 60]
    = 15 : 12 : 10
    Sum of ratios = 15 + 12 + 10 = 37
    ∴  C’s share =
    10
    × 555
    37

    = ₹ 150
    Case II
    A : B : C = 4 : 5 : 6
    Sum of ratios = 4 + 5 + 6 = 15
    ∴  C’s share =
    6
    × 555
    15

    = ₹ 222
    ∴  Required answer
    = ₹ (222 – 150) = ₹ 72

    Correct Option: A

    Case I

    A : B : C =
    1
    :
    1
    :
    1
    456

    =
    1
    × 60 :
    1
    × 60 :
    1
    × 60
    456

    [ LCM of 4, 5 and 6 = 60]
    = 15 : 12 : 10
    Sum of ratios = 15 + 12 + 10 = 37
    ∴  C’s share =
    10
    × 555
    37

    = ₹ 150
    Case II
    A : B : C = 4 : 5 : 6
    Sum of ratios = 4 + 5 + 6 = 15
    ∴  C’s share =
    6
    × 555
    15

    = ₹ 222
    ∴  Required answer
    = ₹ (222 – 150) = ₹ 72


  1. The ratio of the radii of two cylinders is 2 : 3, and the ratio of their heights is 5 : 3. The ratio of their volumes will be









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    r1
    =
    2
    and
    h1
    =
    5
    r23h23

    ∴  Ratio of volumes of cylinders =
    πr12h1
    πr22h2

    =
    r1
    2 ×
    h1
    r2h2

    =
    2
    2 ×
    5
    33

    =
    20
    27

    Correct Option: B

    r1
    =
    2
    and
    h1
    =
    5
    r23h23

    ∴  Ratio of volumes of cylinders =
    πr12h1
    πr22h2

    =
    r1
    2 ×
    h1
    r2h2

    =
    2
    2 ×
    5
    33

    =
    20
    27



  1. When the market price per kg of rice and wheat be in the ratio 3 : 2 , the monthly expenses of a family towards rice and wheat are in the ratio 5 : 6 . If the market price of rice and wheat becomes in the ratio 4 : 3 , what will be the ratio of expenses towards them ? (Assume that amount of rice and wheat consumed remains unaltered .)









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    Market price per kg :
    Rice = Rs . 3x
    Wheat = Rs . 2x
    Monthly expenses :
    Rice = Rs . 5y
    Wheat = Rs . 6y

    Amount of rice =
    5y
    kg
    3x

    Amount of wheat =
    6y
    kg
    2x

    New price :
    Rice = Rs . 4z / kg
    Wheat = Rs . 3z / kg
    ∴  Required ratio
    =
    5y " 4z
    :
    6y
    " 3z
    3x2x

    =
    20
    :
    18
    32

    = 20 : 27

    Correct Option: B

    Market price per kg :
    Rice = Rs . 3x
    Wheat = Rs . 2x
    Monthly expenses :
    Rice = Rs . 5y
    Wheat = Rs . 6y

    Amount of rice =
    5y
    kg
    3x

    Amount of wheat =
    6y
    kg
    2x

    New price :
    Rice = Rs . 4z / kg
    Wheat = Rs . 3z / kg
    ∴  Required ratio
    =
    5y " 4z
    :
    6y
    " 3z
    3x2x

    =
    20
    :
    18
    32

    = 20 : 27


  1. Weekly income of two persons are in the ratio of 7 : 3 and their weekly expenses are in the ratio of 5 : 2. If each of them saves ₹ 300 per week, then the weekly income of the first person is ?









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    Let the income of two persons are 7k and 3k
    Expenditure of first person = 7k - 300
    Expenditure of second person = 3k - 300
    According to the question,
    (7k - 300)/(3k - 300) = 5/2

    Correct Option: C

    Let the income of two persons are 7k and 3k
    Expenditure of first person = 7k - 300
    Expenditure of second person = 3k - 300
    According to the question,
    (7k - 300)/(3k - 300) = 5/2
    ⇒ 14k - 600 = 15k - 1500
    ∴ k = 900
    Income of first person = 7k = 7 x 900
    = ₹ 6300



  1. If (3x – 7 ) : (4x + 3) is sub -triplicate ratio o f 8 : 27, find the value of x .









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    Since (3x – 7 ) : (4x + 3) is the sub -triplicate ratio of 8 : 27,
    therefore ,

    3x − 7
    = 3
    8
    =
    2
    4x + 3273

    ⇒  3 (3x – 7 ) = 2 (4x + 3)
    ⇒  9x – 21 = 8x + 6
    ⇒  9x – 8x = 21 + 6
    ⇒  x = 27

    Correct Option: D

    Since (3x – 7 ) : (4x + 3) is the sub -triplicate ratio of 8 : 27,
    therefore ,

    3x − 7
    = 3
    8
    =
    2
    4x + 3273

    ⇒  3 (3x – 7 ) = 2 (4x + 3)
    ⇒  9x – 21 = 8x + 6
    ⇒  9x – 8x = 21 + 6
    ⇒  x = 27