Aptitude - Alligation or Mixture - Discussion

Can anyone explain me how "Milk in 1 litre mix in 1st can =3/4 litre come?

If it is 6litres of milk and 6litres of water making 12litres of the mix,then does not it mean that milk and water is 50% and 50%??how will it be in the ratio 3:5 to satisfy the requirement??Please explain this..

The ratio given is 3 : 5 water to milk means 5 parts of milk and 3 parts of water in total 8 parts (3 + 5). So mean here is 5/8 because we need to find out the milk percent.

See, first of all understand that the resultant mixture contain water and milk in ratio 3 : 5.

So, water concentration is 3/8 = P (resultant one).
Now we have first mixture (can) water concentration 1/4 = P1.
Similarly second mixture (can) water concentration 1/2 = P2.
Q1/Q2 = (P2 - P)/(P - P1).
Will give the answer as 1 : 1.

So, the answer is B.

Easy method: Take from options

1. Eliminate all answer whose sum is not 12L (here all r 12).
2. 3x/5x new ratio , take option A gives 3 * 4/5 * 8 not equal to 3 : 5.
So, b) 3 * 6/5 * 6 is 3 : 5.

@Amisha, can you explain how we get 5/8?

I'm confusing, please clearly explain the solution.

It's really easy but I can do it in an easier way by another method.

Let one can contain 100 litres of liquid (water + milk).
Now, in the first can, there is 25 l of water and 75 l of milk.
In the second can, there is 50 l of water and 50 l of milk.
Now let he takes y l of liquid from can 1 & y l of liquid from can 2.
Now the quantity of water in this y l of liquid will be ((25/100) y + (50/100) y) = (3/4) y.
But the quantity of water in 12 l of milk is ((3/8) * 12).
Equate (3/4) * y = (3/8) * 12.
y = 6.
So he will take 6 l of liquid from both the cans.

In the first can water and milk ratio is 1 : 3 and in the second it is 1 : 1.

Mixture is 3 : 5 now sub 1/4 and 3/8 (water) it is 1/8. Next 1/2-3/8 it is 1/8 (milk). So the water and milk ratio is 1 : 1. Hence in total of 12 litres 6 litres milk and 6 litres water.