Aptitude - Problems on Ages - Discussion

Ten years hence means ten years from present age or ten years from past.

@Javeed:

The age is calculating with respect to the present age. So ten years ago means 3x-10. So the present age will b 3x+10.

Now after ten years 3x+10+10.

Father's age is twice of his son's age. 8 years ago. He was thrice as old as his son. So what will be d son's age at present.

10 years ago means 3x - 10. But how it become 3x + 10?

What is the meaning of fathers age will be twice that of his son.

2(3x+10+10) = (x+10+10).

Why are you taking?

(3x+10+10) = 2((x+10)+10).

Please tell me.

Let Father = F and Son = S.

10 Years Ago:

F-10 = 3(S-10).
F = 3S-20 ------ (i).

10 year hence:

F+10 = 2(S+10) ------ (ii).

Replace (i) in (ii).

3S-20+10 = 2S+20.
3S-10 = 2S+20.
S = 30 <----- Son's Age.

Again using (i).

F = 3(30)-20.
F = 70.

So Ratio is 70:30 ----> 7:3.

After 10 years from the present > Ankur.

Whats meaning of 10 years hence?

Let the ages of father and son 10 years ago be 3x and x years respectively.

Then, (3x + 10) + 10 = 2[(x + 10) + 10].

3x + 20 = 2x + 40.
x = 20.

Required ratio = (3x + 10) : (x + 10) = 70 : 30 = 7 : 3.

Given, father's age(x) = 3(y)son's age.

y = x/3.

Original equation is, 10 years ago x-10 = 3(y-10).

= 3(x/3-10).....(A).

Given, after 10 years father's age(x) = 2(y)son's age.

y = x/2.

Original equation is, after 10 years x+10 = 2(y+10).

= 2(x/2+10).........(B).

Equating (A) & (B) for present ages, 3(x/3-10) = 2(x/2+10).

x = 80.

y = 40.

These are the ages after 10 years.

Hence, for present ages remove 10 years from both 70:30 or 7:3.