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Option 1 : 14
Given
In a class there are 24 boys whose average age is decreased by 3 months, when 1 boy aged 20 years is replaced by a new boy.
Concept used
Average
Calculation
In a class there are 24 boys whose average age is decreased by 3 months
Sum = 24 × 3 = 72 months
In one year we have 12 months
72 months = 72/12 = 6 years
One boy aged 20 years is repalaced by a new boy.
New boy's age = 20 - 6
Age = 14 years.
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