Question

5 years ago the average age of a family which includes father, mother and a son was 35 years. 3 years ago the average age of father and mother was 46 years. what is the present age (in years) of the son? options: 1) 20

Answer 1

22 years is the age of son

Answer 2

hye
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let mom be m ,son be s and dad be d

5 years ago the average age of a family which includes father, mother and a son was 35 years.

average = sum /no. of observation

lets form an equation

$\frac{(m-5)+(s-5)+(d-5) }{3} = 35$

so the sum of them should be 35*3

=>105 years

= 3 years ago the average age of father and mother was 46 years 

=> $\frac{(m-3)+(d-3)}{2} = 46$

so the sum of them should be 46*2 

=> 92

age of the son => sum of the 1st average - sum of 2nd average

                        => 105 - 92

                         => 13 years

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hope it helps