in a mixture of 120 l of milk,40 l of water is added and ratio of milk to the water is 2:1 .if  this ratio is to be 1: 2,then the quantity of water to be added is 

Dear Student,
Quantity of milk = $60\times \frac{2}{3}=40 litres$

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 =

Now,

 Quantity of water to be added = 60 litres.

Regards