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 chemist mixes two liquids $1$ and $2$. One litre of liquid $1$ weighs $1 \mathrm{~kg}$ and one litre of liquid $2$ weighs $800 \mathrm{gm}$. If half litre of the mixture weighs $480 \mathrm{gm}$, then the percentage of liquid $1$ in the mixture, in terms of volume, is

A container has $40$ liters of milk. Then, $4$ liters are removed from the container and replaced with $4$ liters of water. This process of replacing $4$ liters of the liquid in the container with an equal volume of water is continued repeatedly. The smallest number of times of doing this process, after which the volume of milk in the container becomes less than that of water, is