Aptitude - Ratio and Proportion - Discussion

Total Mixture 60 liter and ration of the milk and water is 2:1.
Then milk is 40 lit and water is 20 lit.

If you go options 40 has to be correct ?
40 : 20 => 40: 20+60 => 40: 80 => 1:2.

How can we assume that the second ratio (1:2) given in the problem for next 60 liters ?

Take it a simple way:

60 litre mixture
2:1 is the ratio means
Mixture is divided into 2+1 = 3 parts i.e, 30lt *3 = 60lt

Given 2:1 = milk: water = 40: 20
Now to make it 1:2
When 40:80=1:2
So, 80-20=60 lt water is added to bring out the ratio.

Old ratio is 2:1.
New ratio is 1:2.

So new ratio is multiply by 2 we get 2:4 (because we want water only).

Old ratio: 2:1.
New ratio: 2:4.

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0:3
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So (3/sum of old ratio) *60=3/3*60=60 is the answer. This method can be applied to all problems like this.

Total mixture is 60ltr which contains milk and water in the ratio 2:1, which means mixture contains 2 parts of milk and 1 part water.

2 parts + 1 part = 3 parts = 60 ltr.

Therefore 1 part =60/3 = 20 ltr.

Milk = 2 parts= 2* 20 =40 LTR.

Water = 1 part=1 * 20 = 20 ltr.

Now quantity of milk and water is changed in such a way to get the new amount of milk and water in the mixture as 1:2.

Now the 1 in 1:2 represent that the amount of milk in the mixture is not changed and it is same as 40ltr. The change is in the amount of water.

Here 1 part in 1:2 represent 40 ltrs of milk. Therefore 2 part 80 ltrs. That is we need 80 ltrs of water to get the new mixture ratio. We have 20 lts of water. Now additional 60 ltrs must be added.

So 60 ltrs is the answer.

Total mixture x=60 ltrs.

a:b=2:1(old ratio) c:d=1:2(new ratio).

x(ad-bc)/c(a+b).

= 60(2*2-1*1)/1(2+1).
= 60(4-1)/3.
= 60*3/3.
= 60 ltrs.

Here is one shortcut for such type of problems.

Given quantity x lit.

Ratio p : q.
Ratio a : b.

Formula is x(pb-qa)/a(p+q).

@Shrikant.

Is this formula applicable of all type of problems?

Guys can anybody help me with this problem. The length and breadth of a rectangle is 57m and 38m respectively. Find the ratio of the length to breadth.

If 60 liters of the water is added, then the mixture contains only water because the mixture is of 60 liters. What about the milk in the mixture?