Five litres of water is added to a certain quantity of pure milk costing Rs. 60 per litre. If by selling the mixture at the same price (Rs. 60 per litre), a profit of 20% was made, then the amount of pure milk in the mixture is:
Answer & explanation
Correct answer: option 4
The correct answer is Option (4) → 25 litres
Let the mixture contain x litres of pure milk. Water costs nothing, so
\( \text{Cost price} = 60x \)
The mixture has x + 5 litres, all sold at Rs. 60 per litre:
\( \text{Selling price} = 60(x + 5) = 60x + 300 \)
\( \text{Profit} = 300 \)
The profit is 20% of the cost price:
\( \displaystyle 300 = \frac{20}{100} \times 60x \)
\( 300 = 12x \)
\( x = 25 \)
So the mixture contains 25 litres of pure milk.