Mixture

A milk vendor has 2 cans of milk. The first contains 25% water and the rest milk. The second contains 50% water. How much milk should he mix from each of the containers so as to get 12 litres of milk such that the ratio of water to milk is 3 : 5?

Let the cost of 1 litre milk be Re. 1

Milk in 1 litre mix. in 1st can =	3	litre, C.P. of 1 litre mix. in 1st can Re.	3
	4		4

Milk in 1 litre mix. in 2nd can =	1	litre, C.P. of 1 litre mix. in 2nd can Re.	1
	2		2

Milk in 1 litre of final mix. =	5	litre, Mean price = Re.	5
	8		8

By the rule of alligation, we have:

C.P. of 1 litre mixture in 1st can   C.P. of 1 litre mixture in 2nd can
3 4	Mean Price 5 8	1 2
1 8		1 8

Ratio of two mixtures =	1	:	1	= 1 : 1.
	8		8

So, quantity of mixture taken from each can =

1/2 x 12

= 6 litres.