Question

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 becomes 26%. The quantity of whisky replaced is: 

• A. $\dfrac{4}{3}$
• B. $\dfrac{3}{4}$
• C. $\dfrac{3}{2}$
• D. $\dfrac{2}{3}$

Hint:

For “replacement” problems, keep total volume constant and track the quantity of solute: new amount $=$ old amount $-$ removed $+$ added.

Answer 1

The Correct Option is D

Let total volume be $V$ and the replaced fraction be $x$.
Alcohol after replacement: \[ 0.40V-0.40xV+0.19xV = 0.40V-0.21xV. \] Given final concentration is $26\%$: \[ 0.40-0.21x=0.26 \;\Rightarrow\; 0.21x=0.14 \;\Rightarrow\; x=\frac{14}{21}=\boxed{\tfrac{2}{3}}. \]