CAT (QA) PYQs

Two alcohol solutions, $A$ and $B$, are mixed in the proportion $1:3$ by volume. The volume of the mixture is then doubled by adding solution $A$ such that the resulting mixture has $72 \%$ alcohol. If solution $A$ has $60 \%$ alcohol, then the percentage of alcohol in solution $B$ is

A container holds 200 litres of a solution of acid and water, having 30% acid by volume. Atul replaces 20% of this solution with water, then replaces 10% of the resulting solution with acid, and finally replaces 15% of the solution thus obtained, with water. The percentage of acid by volume in the final solution obtained after these three replacements, is nearest to

A vessel contained a certain amount of a solution of acid and water. When 2 litres of water was added to it, the new solution had 50% acid concentration. When 15 litres of acid was further added to this new solution, the final solution had 80% acid concentration. The ratio of water and acid in the original solution was