Practice Test Discussion

Q)

Ten years ago, the average age of a family of 4 members was 24 years. Two children having been born, the average age of the family is same today. find the present age of the youngest child, assuming that the children age differ by 2 years?


  • Explanation

    Given,

    The average age of a family 4 members was 24 yrs

    = 24×4= 96 yrs

    Total age of 4 members, 10 years ago

    = [96+(10×4)]

    = 136 yrs

    Two children are born (4 members +2 child)

    = 6×24=144 yrs

    Sum of the ages two children

    = 144-136= 8

    Let the age of younger child be 'x' years

    The age of the elder child =(x+2) years 

    ∴ The present age of the youngest child

    = x(x+2)=8

    = 2x+2=8

    = 2x=6

    = x= 3

    Hence, Option B is correct.

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