Multiple choice

A container contains a 25 L mixture of water and chemical in the ratio of 4 to 1. Extra water and chemical is added to the container, and the ratio becomes 5 : 2. If in this new mixture, the quantity of water added was 15 L more than the chemical added, then what is the quantity of chemical added to the new mixture?

  1. 15 L

  2. 18 L

  3. 30 L

  4. 35 L

  5. 45 L
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A Correct answer
Explanation

Initial mixture: 20L water, 5L chemical. Let added water be W and chemical be C. We have W = C + 15. The new ratio is (20+W)/(5+C) = 5/2. Substituting W, (20+C+15)/(5+C) = 5/2, so (35+C)/(5+C) = 2.5. Solving 35+C = 12.5 + 2.5C gives 1.5C = 22.5, so C = 15.

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