Question

The average age of a committee of seven is same as it was 3 years ago, a young member being substituted for one them. The incoming member is younger to the outgoing member by​

Answer 1

Answer:

Lets assume that the sum of the age of the unchanged trustees 5 years ago be x. Also the age of the replaced trustee and the new trustee, five years ago be y and z respectively.

Now since the average age of the current committee and the previous committee is same,

(x + y)/7=(x + z + 35)/7

The 35 value accounts for the time lapse of 5 years for each of the 7 trustees. 

Thus we get y - z = 35

Therefore the age gap is 35

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