ABC26GN2474 · Percentage
Subject: General Aptitude · Chapter: Percentage · Exam: 2010 · Marks: · Difficulty:
How many litres of a 30\% alcohol solution should be added to 40 litres of a 60\% alcohol solution to prepare a 50\% solution?
Answer
Explanation
Let $x$ litres of 30\% alcohol solution be added. Then, $30 \%$ of $x+60 \%$ of $40=50 \%$ of $(x+40)$ $$\begin{aligned} & \Rightarrow \quad 30 x+60 \times 40=50(x+40) \\ & \Rightarrow \quad 30 x+2400=50 x+2000 \\ & \Rightarrow \quad 20 x=400 \\ & \Rightarrow \quad x=20 . \end{aligned}$$
Explanation as extracted from the printed page; notation may be imperfect.
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