Multiple choice

Two alcohol solutions, A and B, are mixed in the proportion of 1 : 3 by volume. The volume of the mixture is then doubled by adding solution A such that the resulting mixture has 72% alcohol. If solution A has 60% alcohol, then the percentage of alcohol in solution B is ____. (Key in the integer)

  1. 94%

  2. 92%

  3. 90%

  4. 89%
Reveal answer Fill a bubble to check yourself
B Correct answer
Explanation

Let solution A have volume V and solution B have 3V. Total volume = 4V. Adding A to double the volume means adding 4V of A. Total volume = 8V. Total alcohol = (V * 0.60) + (3V * x) + (4V * 0.60) = 8V * 0.72. 0.6 + 3x + 2.4 = 5.76. 3x = 2.76. x = 0.92 or 92%.

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