CAT (QA) PYQs

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 person buys tea of three different qualities at Rs. $800$, Rs. $500$, and Rs. $300$ per kg, respectively, and the amounts bought are in the proportion $2: 3: 5$. She mixes all the tea and sells one-sixth of the mixture at Rs. $700$ per kg. The price, in INR per kg, at which she should sell the remaining tea, to make an overall profit of $50\%$, is

A solution, of volume $40$ litres, has dye and water in the proportion $2: 3$. Water is added to the solution to change this proportion to $2: 5$. If one-fourths of this diluted solution is taken out, how many litres of dye must be added to the remaining solution to bring the proportion back to $2: 3$?