A mixture of 20 kg of spirit and water contains 10 % water.

A mixture of 20 kg of spirit and water contains 10 % water. How much water must be added to this mixture to raise the percentage of water to 25 % ?

As per the given question , we can say that
In first mixture ,

Water =		10	× 20		= 2 kg
		100

and Spirit = 18 kg
In second mixture ,
75 kg spirit is contained in a mixture of 100 kg .

∴ 18 kg spirit is contained in a mixture of	100	× 18		= 24kg
	75

So, water to be added = (24 – 20) kg = 4 kg.