Aptitude - Problems on Ages - Discussion

Let,

Father = X.
Ronit = Y.

1st case:
X = 3Y.

2nd case:
X+8 = Y/2.

Third case:
X+16 = Y.

2X+16 = 3Y. From 1st and second case.

Then subtract third case in it. You will get,

X=2Y.

@Newbie.

You made a wrong calculation 3*16 = 48 and 52+16 = 68.

For all your folks let me tell my method.

First he has given father's age is 3 times of rohit so if rohit age 1, then his fathers will be 1+3=4 i.e. the ratio will be 4:1.

Now after 8 years the ratio given is (2.5) :1.

Now 4-1=3.

2. 5-1=1. 5 for my method you have to keep the difference in two ratios must be same, so multiply (2.5) :1 with 2. It becomes 5:2 i.e. 5-2 = 3 the difference is same as of 4-1=3 now remember we got 5:2 after 8 years i.e 4:1.

8 years hence 5:2

Now 5-4=1= 8 years.

So that makes 40:16.

After further 8 years 48:24 i.e.TWISE (2 times).

Let Ronit's age = x.

Father's age = x+3x (three times more than his son Ronit) = 4x.

After 8yrs.

Ronit's age = x+8.

Father's age = 4x+8.

But father will be two and a half times of Ronit's age so.

4x+8 = 5/2 (x+8).

x = 8.

Further after 8 years.

Ronit's age = x+8+8 = x+16.

Father's age = 4x+8+8 = 4x+16.

We know the value of x is 8 so putting value of x.

Now,

Ronit's age = x+16=8+16=24.

Father's age = 4x+16 = 4*8 +16 = 32+16 = 48.

Now we will calaulate the ratio of father's to ronit's age.

Father's age/ronit's age = 48/24 = 2.

Thus 2 is answer.

2 and a half means 2*1/2 is simplified 2*2=4, and 4+1=5 is come 5/2.

@Poonam And @Thara in question this given that two and half.

Means 2and half which is 2.5 and 5/2 is same equal to 2.5.

Don't get confused in 2/5 and 2.5. Because 2/5 is .4 not 2.5.

Fathers age is 3 times more than his son 4x.

But after getting full stop considering and comparing other sums I can understand like this (x+8). How we put (4x+8) in fathers age?

And as @newbie said, if its correct then I am failing to understand that why is 3x + 8 = 2.5 x ? Shouldn't it be 3x + 8 = 2.5 (x + 8), because even the son's age should have been added to 8 right ?

It doesn't make sense why ppl take the fathers age as 4X just becos its says 'times more' . what if the son's age is 'times less' of the father? :D

So I made a calculation based on logic and it comes to this
son's age = x.
Father's age = X x 3 = 3X.

After 8 years father is 2 and half years older than his son, so if we add 8 years to the fathers age it will be equal to 2 and a half times of the son's age.

i.e 3X + 8 = 2 and a half times of X.
3X + 8 = 2 1/2 x X.

From the equation X = 16.

Now the fathers initial age = 3X.
= 3 x 16 (X=16).
= 52.

After 16 years (8+8 years) father will be,
= 52 + 16.
= 64.

In the same way the son after 16 years will be,
= X + 16.
= 16 + 16 = 32.

Hence the difference of their age will be, 64 divided by 32
= 64 / 32.
= 2.

So the Father will be 2 times older than the son in 16 years :D.

Two and half times means : 2.5.

Multiply both numerator and denominator by 2.

Thus,

2.5 x 2 / 1 x 2.

5/2 or 2.5.