Multiple choice

A vessel contains an 80% alcohol solution. 20% of the solution was removed and replaced with water. If this process is repeated, find the percentage of alcohol which remains in the solution.

  1. 64%

  2. 51.2%

  3. 50.6%

  4. 45%
Reveal answer Fill a bubble to check yourself
B Correct answer
Explanation

Initial alcohol = 80%. Removing 20% of the solution leaves 80% of the original alcohol. This is done twice. Final alcohol = 80% * 0.8 * 0.8 = 80% * 0.64 = 51.2%.

AI explanation

Using the replacement formula, the final quantity of alcohol is Initial Amount multiplied by (1 minus R divided by 100) raised to the power of n, where R is the percentage removed and n is the number of times. Here, the calculation is 80 multiplied by 0.8 squared. This gives 80 multiplied by 0.64, resulting in 51.2 percent.

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