CAT 2020 Slot 1 QA Q26 Ratio, Mixtures & Averages

Question 26 of the Quantitative Ability (QA) section, CAT 2020 Slot 1, with CAT's official answer and a worked solution.

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?

TITA: type in the answer. There are no options and no negative marking.

Answer: 8 Ratio, Mixtures & Averages TITA

Solution

  1. Initially dye 16 L, water 24 L. For 2:5 the water becomes 40 L, total 56 L.
  2. Removing a quarter leaves dye 12 L and water 30 L.
  3. For 2:3 with 30 L water, dye must be 20 L, so add 8 L.

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See every question on Adding a pure component to shift a mixture's concentration.

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