Multiple choice

40 L of a mixture of milk and water contains 10% of water, the water to be added, to make the water content 20% in the new mixture is

  1. 6 L

  2. 6.5 L

  3. 5.5 L

  4. 5 L
Reveal answer Fill a bubble to check yourself
D Correct answer
Explanation

Initial water is 10% of 40L = 4L, so milk is 36L. Let x be the water added. New water is 4 + x, new total is 40 + x. We want (4 + x) / (40 + x) = 0.20. Solving gives 4 + x = 8 + 0.2x, so 0.8x = 4, x = 5L.

AI explanation

The initial mixture contains 10% of 40 L as water, which is 4 L, leaving 36 L of milk. Let x be the amount of water to add; the new total volume is 40 + x, and the new water volume is 4 + x. Set the equation for the new water percentage to 20%: (4 + x) / (40 + x) = 20/100. Solving this equation gives 20 + 5x = 4 + x, so 4x = 16 and x = 5. You need to add 5 L of water.

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