Multiple choice

The concentration of salt in a solution is defined as the number of grams of salt per 100 cc of solution, expressed as a percentage. Two 1200 cc containers are filled with salt solutions having concentrations of 45% and 25%, respectively. A portion of the solution from the first container is removed and replaced with an equal volume from the second container. If the resulting concentration in the first container becomes 33%, what is the volume, in cc, of solution left in the second container?

  1. 420 cc

  2. 240 cc

  3. 720 cc

  4. 480 cc
Reveal answer Fill a bubble to check yourself
D Correct answer
Explanation

Let x be the volume exchanged. The salt in the first container is 0.45 * 1200 = 540. After swapping x, the amount is 540 - 0.45x + 0.25x = 0.33 * 1200 = 396. Solving 540 - 0.20x = 396 gives 0.20x = 144, so x = 720. The volume left in the second container is 1200 - 720 = 480 cc.

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