# Aptitude - Ratio and Proportion - Discussion

Discussion Forum : Ratio and Proportion - General Questions (Q.No. 5)
5.
In a mixture 60 litres, the ratio of milk and water 2 : 1. If this ratio is to be 1 : 2, then the quantity of water to be further added is:
20 litres
30 litres
40 litres
60 litres
Explanation:

 Quantity of milk = 60 x 2 litres = 40 litres. 3

Quantity of water in it = (60- 40) litres = 20 litres.

New ratio = 1 : 2

Let quantity of water to be added further be x litres.

 Then, milk : water = 40 . 20 + x

 Now, 40 = 1 20 + x 2 20 + x = 80 x = 60. Quantity of water to be added = 60 litres.

Discussion:
135 comments Page 1 of 14.

I DON UNDERSTAND..IN 2:1 RATIO MILK IS 40L AND WATER IS 20L..IN 1:2 RATIO,YOU CAN JUST SAY AS MILK 20L AND WATER 40L NO?IF SO,THE WATER THAT IS TO BE ADDED FURTHER FROM THE PREVIOUS MIXTURE TO MAKE IT TO 40L IS JUST 20L NO..?WHY TO DO SUCH CALCULATIONS??

Your plan and all is correct but your thinking is not correct.

in this que., it doesn't say that the new mixture's quantity is same as the before ones(60lr).Also we can't assume 60lr for the new mixture..So, as per the newmix. it's quant. is
water : 2/3 : 80 lr
milk : 1/3 : 40 lr
____________________
total: 120 lr

Mixture = 60 litre
ratio is 2: 1 , so milk:water=40:20
New ration= 1: 2 , means milk : water should be 40:80
Water in the new mixture should be 80
Less water already in the mix 20
Water to be added now is 60

Sonia arif said:   1 decade ago
Thnks ramesh, you told a simple way.

Why have you multiplied 60 (2/3) for quantity of milk? where did the 3 come from?

We have 60 litres of mixture.
Milk & water in the ratio 2:1 that means milk is 2 parts and water is 1
part. Totally mixture contains 3 parts(2+1=3 parts = 60 litres mixture).If we want to know the milk quantity thenwe have the general formula is Total mixture X (milk parts/total parts).

Milk quantity=milk parts/total parts
here milk parts=2
here total parts=milk parts+ water parts=2+1=3

Then milk quantity=2/(2+1);
=2/(3)
=2/3.

2:1 ratio of 60 litre is 40 litre milk and 20 litre water.

i.e 40:20
so to get the ratio 1:2 we should have 40:80
hence we have to add 80-20 (i.e 60) litre of water.

Ramesh I did not understand, can you exp that again.

Emani karthik Reddy said:   1 decade ago
Total milk&water mixture is 60lit
milk&water ratio=2:1
separate milk =(2/3)*60 =40lit
water =(1/3)*60=20lit
new ratio is 1:2