Aptitude - Problems on Ages - Discussion

Ago means we have to subtract 6 then why 6 is added?

Please clear my doubt.

6 years ago Kunal's age was 6x and 6 years ago Sagar's age was 5x.

The ratio 6 : 5 is given here for 6 years ago. Hence, we have to add 6 in the ratio (i.e., 6x + 6 and 5x + 6).

Note (Key point of the solution): If ratio should be given for present then we have to subtract 6 instead of add. But, the ratio is given here for 6 years ago.

Four years hence, Kunal's age will be 6x + 6 + 4 and Sagar's age will be 5x + 6 + 4.

Also, the ratio of their ages will be 11 : 10.

Then, 6x + 10/5x + 10 = 11/10

By solving this we get x = 2.

Hence, 6 years ago Sagar's age was 5x = 5x2 = 10 years and for the present, we have to add 6.

So, the present age of Sagar is 10 + 6 = 16 Years.

After getting x=2.

In Q, we have to calculate the present age of Sagar.

Why it's 5x+6?

Is it 6 years ago na?

It must be.

5x = 5 (2) =10.

I'm confused someone help me.

If it is 6 years ago, the ratio should be subtracted by 6. Why is it added here? Can anyone explain?

Let present ages of Kunal and Sagar be x & y respectively.

(x - 6) / (y - 6)=6/5 -----> ratio of ages 6 years back.
(x + 4) / (y + 4)= 11/10 -----> ratio of ages 4 years hence.

If we solve them simultaneously, Sagar's present age comes out to be 18 & Kunal's as 16.

So, why is this solution wrong? Someone explain me.

6 years ago -> present -> after 4 years.
Their age are;
6x and 5x.
(6x + 6) and (5x+6).
Then ((6x + 6) + 4)) and ((5x + 6) + 4)).

Here Kunal : Sagar
6x + 6 + 4: 5x + 6 + 4.
11 : 10.

Cross multiplication
60x + 100 = 55x + 110.
5x = 10.
x = 2 so Sagar present age is 5x + 6.
Here x = 2. So 5 * 2 +6 = 16.

8 years ago Bhanu age was four greater than Ravi age that time also of the ratio of Ravi age to Bhanu 8 years after will be 6:7 find the ratio of Ravi age to that of Bhanu age 4 years after.

Before 6 years Kunal's age is 6x.
After 6 years Kunal's age is 6x + 6.

Before 6 years Sagar's age is 5x.
After 6 years Sagar's age is 5x + 6.

Hence after 4 years from the present.

=> (6x + 6 + 4)/(5x + 6 + 4) = 11/10.
=> (6x + 10) * 10 = (5x + 10) * 11.
=> solving above we get x = 2.

Now Sagar's age at present is "5x + 6" right.

Therefore Sagar's age = 5 (2) + 6 = 16.

According to me, the age of Sagar is 20.