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The amount of water (in ml) that should be added to reduce 9 ml. Lotion, containing 50% alcohol, to a lotion containing 30% alcohol, is__________?

Correct answer: D. 6

  • A. 3
  • B. 4
  • C. 5
  • D. 6

Explanation

The 9 ml lotion contains 50% alcohol, so alcohol volume is 50/100 x 9 ml = 4.5 ml. For this to be 30% of the final mixture, the final volume must be 4.5 ml/0.30 = 15 ml, so water added = 15 ml - 9 ml = 6 ml. The likely trap is 3 ml, which does not dilute 4.5 ml of alcohol to 30% of the final volume.

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