A dishonest milkman professes to sell his milk at cost price but he mixes it with water and thereby gains 25%. The percentage of water in the mixture is:

Question:
A dishonest milkman professes to sell his milk at cost price but he mixes it with water and thereby gains 25%. The percentage of water in the mixture is:

[A].

4%

[B].

6%

[C].

20%

[D].

25%

Answer: Option C

Explanation:

Let C.P. of 1 litre milk be Re. 1

Then, S.P. of 1 litre of mixture = Re. 1, Gain = 25%.

C.P. of 1 litre mixture = Re.		100	x 1		=	4
		125				5

By the rule of alligation, we have:

C.P. of 1 litre of milk C.P. of 1 litre of water
Re. 1	Mean Price Re. 4 5	0
4 5		1 5

Ratio of milk to water =	4	:	1	= 4 : 1.
	5		5

Hence, percentage of water in the mixture =		1	x 100	%	= 20%.
		5