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Railways PYQCBT 1 2020

RRB NTPC · Question 62

A mixture contains acid and alcohol in the ratio of 3 : 2. On adding 10 litres of alcohol in mixture, the ratio of acid to alcohol becomes 3 : 5. The quantity of acid (in litres) in the original mixture was:

  1. 5

  2. 4.5

  3. 5.5

  4. 10

Show answer & explanation

Answer: (D) 10

Explanation

Let acid = 3x and alcohol = 2x. Then 3x/(2x + 10) = 3/5, so 15x = 6x + 30 and x = 10/3. Acid = 3x = 10 litres.