Multiple choice

A mixture contains 80% acid and rest water. The part of the mixture that should be removed and replaced by the same amount of water to make the ratio of acid and water 4:3 is

  1. $2/7$
  2. $3/7$
  3. $1/3$
  4. $2/3$
  5. $2/5$
Reveal answer Fill a bubble to check yourself
A Correct answer
Explanation

Let x be the fraction removed. Initial acid = 0.8. After removal and replacement: acid = 0.8(1-x). We need acid:water = 4:3, so acid fraction = 4/7. 0.8(1-x) = 4/7. Solving: 0.8 - 0.8x = 0.571, so 0.8x = 0.229, x = 0.286 = 2/7. Option A is correct.

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