How much water must be added to 60 litres of milk at 3/2 litres for Rs. 20 so as to have a mixture worth Rs. 32/3 a litres?Options :12 L15 L18 L20 L

The problem is asking how much water (which is free) we need to add to the milk to decrease the price per litre from Rs. 20 to Rs. 32/3.

First, let's find out the cost of 60 litres of milk. Since the milk is Rs. 20 for 3/2 litres, we can calculate the cost of 60 litres by setting up a proportion:

(20 Rs / 3/2 litres) = x Rs / 60 litres

Solving for x gives us the total cost of the milk:

x = 20 Rs * (60 litres / 3/2 litres) = 800 Rs

Next, we want to find out how many litres of the mixture we would have if it were worth Rs. 32/3 per litre. We can set up another proportion using the total cost of the milk (800 Rs):

(32/3 Rs / 1 litre) = 800 Rs / y litres

Solving for y gives us the total litres of the mixture:

y = 800 Rs * (1 litre / 32/3 Rs) = 75 litres

Finally, to find out how much water we need to add, we subtract the original 60 litres of milk from the total 75 litres of the mixture:

75 litres - 60 litres = 15 litres

So, we need to add 15 litres of water to the milk to get a mixture worth Rs. 32/3 per litre. Therefore, the correct option is 15 L.