Multiple choice

A large vessel contained a mixture of 500 ml of strawberry extract and water. 100 ml of this mixture is poured into the other beaker and the same quantity is replaced by water. The percentage of strawberry extract in the vessel is 64%. Find the percentage of strawberry extract initially in the mixture.

  1. 20%

  2. 25%

  3. 60%

  4. 80%

  5. 85%
Reveal answer Fill a bubble to check yourself
D Correct answer
Explanation

Let initial concentration be x. After replacing 100ml (1/5 of total) with water, concentration becomes x * (1 - 100/500) = 0.8x. We are told 0.8x = 0.64. x = 0.64 / 0.8 = 0.8, which is 80%.

AI explanation

Using the mixture replacement formula, Final Concentration equals Initial Concentration multiplied by (1 minus Replaced Volume divided by Total Volume) raised to the power of n. Substituting the given values gives 0.64 equals Initial Concentration multiplied by (1 minus 100 divided by 500) squared, simplifying to 0.64 equals Initial Concentration multiplied by 0.8 squared. Solving for the initial concentration gives 0.64 divided by 0.64, which equals 0.8, meaning the initial percentage of strawberry extract was 80%.

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