CAT (QA) PYQs

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

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

If a certain weight of an alloy of silver and copper is mixed with $3$ kg of pure silver, the resulting alloy will have $90\%$ silver by weight. If the same weight of the initial alloy is mixed with $2$ kg of another alloy which has $90\%$ silver by weight, the resulting alloy will have $84\%$ silver by weight. Then, the weight of the initial alloy, in kg, is