Pure milk costs 3.60 per litre. A milkman adds water to 25 litres of pure milk and sells the mixture at 3 per litre. How many litres of water does he add?  Choices.
A) 2 litres  B) 5 litres  C) 7 litres  D) 11 litres  E) None of these
In mixture,   Quantity of pure milk /Quantity of water=3−0/3.6−3=3/0.6= 
<gadget id="calculator">3/0.6</gadget>
<output>5</output>
5/1   Since in every 5 litres of milk, he adds 1 litre of water.   ∴ In every 25 litres of milk, he adds 5 litres of water.   Answer 5 litres
<result>B</result>
Pure milk costs 3.60 per litre. A milkman adds water to 25 litres of pure milk and sells the mixture at 3 per litre. How many litres of water does he add?