Aptitude - Problems on Ages - Discussion

1. If at the time of father's age @15 years, his son was born, at that time son age is @1 year.

If father come into age @30 years, his son age is @15 years.

2. If at the time of father's age @20 years, his son was born, at that time son age is @1 year.

If father come into age @40 years, his son age is @20 years.

3. If at the time of father's age @19 years, his son was born, at that time son age is @1 year.

If father come into age @38 years, his son age is @19 years.

Finally that 19 years is present age of son.

But they are asking 5 years ago so, 19 years - 5 years = 14 years.

How can we use same variable for both son's present age and father's age at the time of birth?

"I was as old as you are at the present at the time of your birth" means that at the time of son birth father age was equal to present son age. So father age is now double of son age. Father's age now 38 year.

If son age is x then father's age = 2x.

Given that father's age = 38.

So, 2x = 38.

=> x = 19.

5 year back is x-5.

i.e 19-5 = 14.

Here is the clarity:

Let present age of son = x.

Given father present age = 38.

According to logic when son age is 0 (during birth), fathers age is x.

Then when son's age is x, then father's age is 38.

So x-0 = 38-x.
2x = 38.
x = 19.

Then 5 years back of son's age it will be 14 years.

Hope you understood.

38-x age of father at born time.

@All.

Simply the calculation is; (father's present age - sons present age) = father's age at the time of birth.

But father's age at the time of the birth of his son = son's present age.

@ALL.

X going to other side gives x and x give 2x here.

How? Explain the solution.

let's use ratio method.

Father : Son
38 : X
X : 0

Now do cross multiplication.
i.e. 2X=38 => X=19.
Five years back, the son's age is 19-5=14.

How did you formed (38-x) =x?