He needs to drink 3 cups MORE to meet his daily requirement.
Step-by-step explanation:
Here, as given in the question:
The total need for water = half a gallon = 0.5 gallon
1 gallon = 128 oz
So, 0.5 gallon = 128/2 = 64 oz
Now, the capacity of 1 cup = 3.5 oz
The number of cups already drank by the person = 15 cups
So, the total amount of water already taken by him
= 15 cups x Capacity of 1 cup
= 15 x (3.5 oz) = 52.5 oz
So, the amount of water left to be drink by him
= Total Need - Already covered
= 64 oz - 52 . 5 oz = 11.5 oz
Now, as 1 cup = 3.5 oz
So, 11.5 oz has cups = 3.28 cup≈ 3 cups
Hence, he needs to drink 3 cups MORE to meet his daily requirement.