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200 litres of alcohol solution has 30% alcohol in it. How much alcohol should be added to make it 50% in the solution? 

200 litres of alcohol solution has 30% alcohol in it. How much alcohol should be added to make it 50% in the solution?  Correct Answer 80

Amount of solution = 200 litre

Percentage of alcohol = 30%

∴ Amount of alcohol in the solution = (0.30 × 200) litre = 60 litre

Amount of the other component of the solution = (200 – 60) litre = 140 litre

∴ Amount of alcohol should be added to make it 50% in the solution

= (140 – 60) litre

= 80 litre

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