Cost of mixture = Total Cost ∕ Total Quantity Solution: We know that price of water is zero. Cost of milk = Rs 29 per litre Cost of water = Rs 25 per litre Let the ratio of milk and water be x:1 Then, (1×0)+(x×29)=(1+x)×25 0+29x=25+25x 29x−25x=25 4x=25 x=25∕4