Latest IBM Aptitude Question SOLUTION: If average age of a five member group is same as three years ago. When a old man is replaced by a young man. What is the diff. between their ages.

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If average age of a five member group is same as three years ago. When a old man is replaced by a young man. What is the diff. between their ages.

Asked In IBM aditi sharma (12 years ago)

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Ankit  (12 years ago)

let the current age are = (younger)a,b,c,d,e(older)
and average age= n = a+b+c+d+e/5
average age 5 years ago = a+b+c+d+e-15/5
As it given its equal to average age if old man replace by young man..
so, a+b+c+d+e/5 = a+b+c+d+a-15/5
=>a+b+c+d/5 + e/5 = a+b+c+d/5 + a-15/5
=> e/5 = a-15/5
=> e-a=15

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c k maunik  (12 years ago)

three years ago average is x and now also it is x but the younger person is replaced by older person it implies that answer = (No of persons)*time elapsed = 5*3 = 15.

so answer is 15

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uthra murugesan  (8 years ago)

12 years
5*3=15 yrs
4*3= 12 yrs

refer this example-
Let the old member be x
Remaining member be y
New member be z
Average ages be a

(x+9y)/10=a; --------------------(1)
4 years later
(9y +z+36)/10=a--------------(2) //36 because collective ages of 9 person 4 years after
solving 1 and 2 you get

You get z+36=x
This means x is 36 year older then z

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