Multiple choice

A vessel has 60 litres of solution of acid and water, having 80% acid. How much water will be added to make it a solution in which acid forms 60%?

  1. 48 litres

  2. 20 litres

  3. 36 litres

  4. None of the above
Reveal answer Fill a bubble to check yourself
B Correct answer
Explanation

Initial acid = 0.8 * 60 = 48 litres. Let x be water added. New total = 60 + x. Acid concentration = 48 / (60 + x) = 0.6. 48 = 36 + 0.6x. 12 = 0.6x. x = 20 litres.

AI explanation

Using the method of alligation on the acid percentages, compare the initial 80% acid solution to pure water at 0%. The target mixture must have 60% acid, so the ratio of acid solution to water is (60 - 0) : (80 - 60), which is 60 : 20 or 3 : 1. Since the initial 60 liters represents 3 parts, 1 part equals 20 liters of water to be added.

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