The ratio of milk and water in 85 kg of adulterated milk

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The ratio of milk and water in 85 kg of adulterated milk is 27 : 7. The amount of water which must be added to make the ratio 3 : 1 is ?

1. 5 kg
2. 6.5 kg
3. 7.25 kg
4. 8 kg

Correct Option: A

Milk = 85 x (27/34) kg = 135/2 kg = 67.5 kg
Water = 85 x (7/34) kg = 35/2 kg = 17.5 kg

Let Amount of water to be added is x,
∵ 67.5 / (17.5 + x) = 3/1
⇒ 3 (17.5 + x) = 67.5
∴ x =5
∴ Water to be added = 5 kg.