To solve this problem, we need to determine how much water should be added to 60 liters of milk, initially priced at 1 rupee per liter, to create a mixture where the price per liter remains 1 rupee.

However, since the initial price of the milk is already 1 rupee per liter and the water has no cost (because it's free in this scenario), no water should be added to maintain the price of 1 rupee per liter for the entire mixture. If water is added, it would reduce the overall value of the mixture, which is not the requirement here.

Thus, the correct answer is:

• No water should be added to the 60 liters of milk to maintain a price of 1 rupee per liter.

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Would you like further details or have any additional questions?

Here are 5 related questions you might find interesting:

1. What happens if we add water to milk at 1 rupee per liter?
2. How does the price of a mixture change when diluting milk with water?
3. If we added sugar to the milk, how would the mixture price change?
4. How do you calculate the final price of a mixture of liquids with different prices?
5. What are the practical applications of mixture problems in daily life?

Tip: Always remember, in mixture problems, if one component is free, the value of the mixture depends on the proportion of the costly component.