Question

In what proportion water be mixed with spirit to gain 12.5% by selling it at cost price?

• A. 3 : 5
• B. 1 : 8
• C. 2 : 7
• D. 1 : 9

Answer 1

The correct option is B 1 : 8

Let, CP = Rs. 100, then SP = Rs. 112.5
Hence, CP : SP = 100 : 112.5
$\therefore$ Proportion of amount of solution in both the cases = 100 : 112.5 = 8 : 9
$\therefore$ Proportion of water need to be mixed to spirit = $\frac{(9-8)}{8}=\frac{1}{8}$


Alternative Approach:
Profit $=12.5\%=\frac{1}{8}$
Hence the ratio of water to spirit is 1 : 8
Since profit $\%=\frac{profit}{cost}\times 100$