A jar full of whisky contains 40% alcohol. A part of this whisky is replaced by another containing 19% alcohol and now the percentage of alcohol was found to be 26%. The quantity of whisky replaced is:

Answer: Option B

By the rule of alligation, we have:

So, ratio of 1^st and 2^nd quantities = 7 : 14 = 1 : 2
∴ Required quantity replaced = $$\frac{2}{3}$$