Pure milk costs Rs. 80 per litre. A milkman adds water to 30 litres of pure milk and sells the mixture at Rs. 60 per litre without any overall loss or gain. How many litres of water does he add?
Answer & explanation
Correct answer: option 3
The correct answer is Option (3) → 10 litres
The cost of the milk is
\( \displaystyle 30\times 80=\text{Rs. }2400 \)
For no gain or loss, the mixture must sell for Rs. 2400. At Rs. 60 per litre, its volume is
\( \displaystyle \frac{2400}{60}=40\text{ litres} \)
So the water added is 40 − 30 = 10 litres.