question_answer

In what proportion must water be added to spirit to gain 20% by selling it at the cost price?

A) 2 : 5

B) 1 : 5

C) 3 : 5

D) 4 : 5

Correct Answer: B

Solution :

[b] Let the CP be Rs. 1 per litre. SP of 1 L of mixture = Rs. 1, Gain per cent = 20% CP of 1 L of mixture \[=\left( \frac{100}{120}\times 1 \right)\]                   \[=\text{Rs}.\,\,\frac{5}{6}\] Ratio of water and spirit       \[=\frac{1}{6}:\frac{5}{6}=1:5\]