Important word problems on Linear Equations in two variables 8

Question for practice
The following questions are more helpful for class tenth students for all boards.

Questions 8    The ratio of the ages of the father and the son at present is 6 : 1. After Five years, the ratio will become 
7 : 2. What is the present age of son?

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Comments

  1. Unknown11 August 2012 at 06:01

    Let the present of father be x
    Let the present of his son be y

    The ratio of their present ages is 6:1
    x/y=6/1
    x=6y
    x-6y=0 1

    the ratio of their ages after 5 years will be 7:2

    x+5/y+5=7/2
    2(x+5)=7(y+5)
    2x+10=7y+35
    2x-7y=35-10
    2x-7y=25 2

    eqn1*2 -eqn2
    2x-21y=0
    2x-7y=25
    - + -
    -5y=-25
    y=5
    Substituting y=5 in eqn 1
    x-6(5)=0
    x-30=0
    x=30
    the present age of father is 30 years
    the present age of his son is 5 years

    ReplyDelete
  2. Unknown11 August 2012 at 06:09

    Ans. Let father's present age = x years
    Let son's present age = y years
    x/y = 6/1
    or x-6y = 0 ......(1)
    x+5/y+5 = 7/2
    or 2x+10 = 7y+35
    or 2x-7y = 25 .....(2)
    by elimination from (1) and (2),
    y = 5
    therefore , Son's present age = 5 years

    ReplyDelete
  3. Unknown11 August 2012 at 07:56

    Let father's present age = x years
    Let son's present age = y years
    x/y = 6/1
    or x-6y = 0 (1)
    x+5/y+5 = 7/2
    or 2x+10 = 7y+35
    or 2x-7y = 25 (2)
    by eliminating from (1) and (2),
    y = 5
    therefore , Son's present age = 5 years

    ReplyDelete
  4. Unknown11 August 2012 at 10:23

    solution

    father's age = x years
    sons's age = y years
    x/y = 6/14
    => (1).... x-6y=0
    => x+5/y+5=7/2
    => 7y+35=2x+10
    => (2).... 2x-7y=25
    by eliminating from (1) and (2)
    y = 5

    therefore => sone's age will be 5 years

    ReplyDelete
  5. Unknown11 August 2012 at 21:38

    let fathrs present age =x
    let sons present age =y
    x-6y=0 -I
    2x-7y=25 -II
    eliminating I & II we get
    y=5
    x=30

    ReplyDelete
  6. Unknown13 August 2012 at 07:43

    age of father=6x
    age of son=x
    after 5 yrs
    age of father=6x+5
    age of son=x+5
    ratio=7:2
    6x+5/x+5=7/2
    12x+10=7x+35
    5x=25
    x=5
    present age of son=5 yrs

    ReplyDelete
  7. Manan Raheja19 August 2012 at 05:40

    Let the son's age = y years
    " " father's age = x years

    So, x = 6y
    => x - 6y = 0
    => 2x - 12y = 0........(1)

    Also, 2(x + 5) = 7(y + 5)
    => 2x + 10 = 7y + 35
    => 2x - 7y = 25.........(2)

    Eliminating (1) and (2) we get
    y = 5 and x = 30!!!

    THANKS!!!

    ReplyDelete

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