Multiple choice

The contents in beakers A and B are 80 cm3 of sugar and 80 cm3 of sand, respectively. Now, 20 cm3 of sugar is taken out from A and put into B. After thorough mixing, 20 cm3 of the mixture is taken out from B and put into A. Find the percentage of sand in the mixture in beaker A.

  1. 15%

  2. 20%

  3. 21%

  4. 25%
Reveal answer Fill a bubble to check yourself
B Correct answer
Explanation

Beaker A: 80 sugar. Beaker B: 80 sand. Move 20 sugar to B: A has 60 sugar, B has 80 sand + 20 sugar. Mix B: 100 total, 80% sand, 20% sugar. Move 20 of mixture to A: 20 * 0.8 = 16 sand moved to A. A now has 60 sugar + 16 sand + 4 sugar = 64 sugar + 16 sand. Total in A = 80. Sand percentage = 16/80 = 20%.

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