A jar full of whisky contains 40% alcohol. A part of this whisky is replaced by another containg 19% alcohol and now the percentage of alcohol was found to be 24%. What quantity of whisky is replaced ?  Answers
A) 1 / 3  B) 2 / 3  C) 2 / 5  D) 3 / 5  E) 16 / 21

Rationale: "let us assume the total original amount of whiskey = 10 ml - - - > 4 ml alcohol and 6 ml non - alcohol . let x ml be the amount removed - - - > total alcohol left = 4 - 0.4 x new quantity of whiskey added = x ml out of which 0.19 is the alcohol . thus , the final quantity of alcohol = 4 - 0.4 x + 0.19 x - - - - > ( 4 - 0.21 x ) / 10 = 0.24 - - - > x = 160 / 21 ml . per the question , you need to find the x ml removed as a ratio of the initial volume - - - > ( 160 / 21 ) / 10 = 16 / 21 . hence , e is the correct answer ."
Answer: E