A jar full of whisky contains 30 % alcohol. A part of this whisky is replaced by another containing 20 % alcohol and now the percentage of alcohol was found to be 22%. The quantity of whisky replaced is:

\[\frac{4}{3}\] \[\frac{3}{4}\] \[\frac{1}{2}\] \[\frac{2}{5}\]

\[\frac{1}{2}\]

Let C = 30% , D = 20% and M = 22% Then the quantity is (M-D)/(C-M)