Find the Ratio Between Younger Brother and Elder Brother

The sum of the ages of two brother, having a difference of 8 years between them, will double after 10 years, What is the ratio of the age of the younger brother to that of the elder brother ?

  1. 8:9
  2.   10:13
  3.   7:11
  4.   3: 7

 

Manish Listener Asked on 21st June 2015 in Maths.
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  • 1 Answer(s)

    Answer: (4) 3:7

    Explanation:-
    Let the age of elder brother be x years and smaller brother be y years.
    Then, According to first condition,
    x – y = 8 —– (i)
    and sum is x+y
    Again, it is given that the sum of their ages will double after 10 years. The equations thus formed is
    2(x+y) = (x+10) + (y+10)
    Thus, 2x + 2y = x+y+20
    x+y=20 —— (ii)
    adding (i) and (ii), we get
    2x = 28
    x = 14 years
    and y is 14- 8 = 6 years
    Therefore, ratio of younger to elder brother is 6/14 = 3/7

    Then, the ration of the age of the younger brother to that of the elder brother = 3 : 7.

    Hence, the answer is (4) 3 : 7.

    Anurag Mishra Professor Answered on 4th September 2015.
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