IIM-B (BBA-DBE) 2025 #1 (QA) PYQs

How many liters of water should be added to a $30$ liters mixture of milk and water containing milk and water in the ratio $7:3$ such that the resultant mixture has 40% water in it?

An alloy $P$ has copper and zinc in the proportion of $5:2$ (by weight), while another alloy $Q$ has the same metals in the proportion of $3:4$ (by weight). If these two alloys are mixed in the proportion of $a:b$ (by weight), a new alloy $R$ is formed, which has equal contents of copper and zinc. Then, the proportion of copper and zinc in the alloy $S$, formed by mixing the two alloys $P$ and $Q$ in the proportion of $b:a$ (by weight) is

A mixture of alcohol and water contains 35% alcohol by weight. if 25 g water is added to such a mixture of 100 g, then the percentage of alcohol in the mixture is