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Question

A mixture of corn flakes and milk of 3 litres contains 80% cornflakes. X litres of water must be added to this mixture to raise the percentage of water to 30%. Find X? (Assuming 1kg equals to 1 litre in this problem).

  • 0.50
  • 0.42
  • 0.30
  • 0.28
Answer- A

Water in the given mixture = 20*3/100 = 3/5 litre,

And cornflakes = (3-3/5) = 12/5 litre

Let x litres of water added, Then, (x+(3/5))/(3+x) *100 = 30

(x+(3/5))/(3+x) = 30

(5x+3)/(15+5x) = 3/10

50x+30 = 45+ 15x

30x = 15

x = 0.5 litre