Multiple choice

In a $729\ ml$ mixture milk and water are in the ratio of $7 : 2$. How much quantity of water should be added in the new mixture so that the ratio of milk and water becomes $7 : 3$ ?

  1. $72 ml$
  2. $81 ml$
  3. $85 ml$
  4. $90 ml$
Reveal answer Fill a bubble to check yourself
B Correct answer
Explanation

Initial mixture is 729 ml with ratio 7:2. Milk = (7/9)*729 = 567 ml, Water = (2/9)*729 = 162 ml. Let x be the water added. New ratio: 567 / (162 + x) = 7 / 3. Cross-multiplying: 1701 = 7 * (162 + x) => 1701 = 1134 + 7x => 567 = 7x => x = 81 ml.

AI explanation

The mixture contains milk and water in the 7:2 ratio, meaning water is 2/9 of the 729 ml mixture, or 162 ml, and milk is 567 ml. Let x be the water added; the new ratio is 567/(162+x) = 7/3. Solving for x gives 1701 = 1134 + 7x, so 7x = 567 and x = 81 ml.

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