A milk man diluted milk to an extent of 25% of the original volume of pure milk with water and priced it same as the cost price of milk. Part of the water evaporated and the volume was reduced to $$\frac{23}{25}th$$ of the diluted volume. The profit percent to the milk man is

Let original quantity of pure milk = 100x

Let cost price of '100x' litres of pure milk = 100

Amount of water added = 25% of 100x = 25x

Total quantity of mixture = 100x + 25x = 125x

Total quantity of mixture after evaporation = $$125x * \frac{23}{25} = 115x$$

Selling price of '115x' litres of mixture = Cost price of '115x' litres of pure milk = 115x

Profit amount = 115x - 100x = 15x

Profit % = $$\frac{15x}{100x} * 100$$ = 15%