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
Given:
Total liquid = 120 liters
Initial alcohol content = 30%
According to the formula:
Percentage = (Amount of alcohol / Total quantity) × 100
Initial alcohol = 30% of 120 = 36 liters
30 liters of the mixture was withdrawn
Alcohol withdrawn = 30% of 30 = 9 liters
Remaining alcohol = 36 − 9 = 27 liters
Now, 30 liters of 50% alcohol was added
Alcohol added = 50% of 30 = 15 liters
New alcohol content = 27 + 15 = 42 liters
Percentage = (42 / 120) × 100 = 35%