A 50-litre solution of alcohol and water has 20% water. How many litres of alcohol must be added to make the water content 10%?
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Correct answer: D
Explanation
The correct answer is option 4 i.e. 50 litres
Initial water = (20/100) × 50 = 10 litres
Let alcohol be added = x liters
So, 10/(50 + x) = 10/100
⇒ 1000 = 500 + 10x
⇒ 10x = 500
⇒ x = 50 litres