SOLUTION: The average age of a group of 20 boys is increased by one year when 5 of them whose average age was 20 years are replaced by 5 new boys. The average age of new comers is

Question 725586: The average age of a group of 20 boys is increased by one year when 5 of them whose average age was 20 years are replaced by 5 new boys. The average age of new comers is
Answer by god2012(113) (Show Source): You can put this solution on YOUR website!
Solution:
Let 'x' be the sum of ages of first 20 boys.
Let 'y' be the sum of ages of 5 old boys and
'z' be the sum of ages of 5 new boys.
Given : y/5 = 20 or y = 100
(x - y + z) / 20 = 1 + (x/20)
(x-100 +z)/20 = (x/20) + 1
or z/20 = 6 or Z = 120
Average of 5 new comers = Z / 5 = 120 / 5 = 24 years
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