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While preparing an alcohol-water solution with 30% alcohol, accidently, more alcohol was mixed, and a solution containing 40% alcohol was made. How much water should be added in 20 litres of the prepared solution to obtain the desired solution?

While preparing an alcohol-water solution with 30% alcohol, accidently, more alcohol was mixed, and a solution containing 40% alcohol was made. How much water should be added in 20 litres of the prepared solution to obtain the desired solution? Correct Answer 20/3 litres

Let the amount of water to be added be ‘x’ litres

Amount of alcohol in 20 litres of prepared solution = 40% of 20 = 8 litres

After adding ‘x’ litres of water in 20 litres of solution, alcohol should be 30% of the final solution

⇒ Amount of alcohol in final solution = 30% of (20 + x) = (6 + 0.3x) litres

∵ The amount of alcohol remains the same,

⇒ 6 + 0.3x = 8

⇒ 0.3x = 2

⇒ x = 2/0.3 = 20/3 litres

∴ Amount of water to be added is 20/3 litres 

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