SSC CPO SI and ASI 2015 Paper

(4) Let there be 3 litres, 2 litres and 1 litre of mixtures in the three vessels 1, 2, and 3, respectively.
From vessel- 1 litre of mixture is taken, in which milk is $\frac{5}{7}\mathit{l}$ andwater is $\mathrm{}\frac{2}{7}\mathit{l}$.
From vessel-2, 1 litre of mixture is taken, in which milk is $\frac{4}{5}\mathit{l}$ and water is $\frac{1}{5}\mathit{l}$
From vessel-3, $\mathrm{}\frac{1}{7}$ litre of mixture is taken, in which milk is $\frac{1}{7}\times \frac{4}{5}=\mathrm{}\frac{4}{35}\mathit{l}$ and water is $\mathrm{}\frac{1}{7}\times \mathrm{}\frac{1}{5}=\mathrm{}\frac{1}{35}\mathrm{}\mathit{l}$
Total quantity of the new mixture$=1+1+\frac{1}{7}=\frac{15}{7}\mathit{l}$
Percentage of water in the new mixture $=\mathrm{}\frac{\mathrm{}\frac{2}{7}+\mathrm{}\frac{1}{5}+\mathrm{}\frac{1}{35}}{\mathrm{}\frac{15}{7}}\times 100$
$=\mathrm{}\frac{\mathrm{}\frac{18}{35}}{\mathrm{}\frac{15}{17}}\times 100=\mathrm{}\frac{18}{75}\times 100=24\%$