A tank contains 120 litres of liquid, 30% of which is alcohol. If 30 litres of this mixture is replaced by another liquid containing 50% alcohol, what is the percentage of alcohol in the resulting solution?
Show answer & explanation
Correct answer: B
Explanation
The correct answer is option 2 i.e. 35%.
Initial alcohol = 30/100 × 120 = 36 L
Remove 30 L mixture: Alcohol removed = 30/100 × 30 = 9 L
Alcohol left = 36 – 9 = 27 L
Alcohol added = 1/2 × 30 = 15 L
New alcohol = 27 + 15 = 42 L
Total volume = 120 L
Percentage of alcohol= (42/120) × 100 = 35%