question_answer

In what ratio must water be mixed with milk to gain 10% by selling the mixture at cost price?

A) 3 : 2     

B)  5 : 4   

C)  9 : 7    

D)  1 : 10

Correct Answer: D

Solution :

Let the CP of milk be Rs. 1 /L Then, SP of 1 L of mix = Rs. 1, gain = 10% CP of 1 L of mix = Rs. \[\left( \frac{100}{110}\times 1 \right)\]= Rs. \[\frac{10}{11}\] By Rule of allegation, we have Ratio of water and milk \[=\frac{1}{11}:\frac{10}{11}=1:10\]