Multiple choice

How many litres of water must be added to a 20-litre mixture of milk and water with 10% water to make the water content 25%?(a) 2 litres(b) 3 litres(c) 4 litres(d) 5 litres(e) 6 litres

  1. D

  2. E

  3. C

  4. B

  5. A
Reveal answer Fill a bubble to check yourself
C Correct answer
Explanation

Initial mixture: 20L total, 10% water = 2L water, 18L milk. Let x be added water. New water = 2+x, total = 20+x. (2+x)/(20+x) = 25/100 = 1/4. 8 + 4x = 20 + x => 3x = 12 => x = 4.

AI explanation

In the 20-litre mixture, the 10 percent water content translates to 2 litres of water and 18 litres of milk. Let the volume of water to be added be x litres, making the new total volume (20 + x) litres; since the water must become 25 percent of the new mixture, the equation is (2 + x) divided by (20 + x) equals 0.25. Multiplying by the denominator gives 2 + x equals 5 + 0.25x, and solving for x yields 0.75x equals 3, so x equals 4 litres.

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