In a mixture of milk and water the proportion of water by weight was 75 If in 60 gm of mixture 15 gm...........

Explanation:

Water in 60 gm mixture=60 x 75/100 = 45 gm. and Milk = 15 gm.

After adding 15 gm. of water in mixture,

total water = 45 + 15 = 60 gm

and weight of a mixture = 60 + 15 = 75 gm.

So % of water = 100 x 60/75 = 80%.

Hence, option 4 is the correct answer.