I would say it's 3/8 of a cup because if you multiply 3/4 by 2 it would be 6/8. It's the same amount but just a different measurement. Now just take 3 away from 6/8 and you have 3/8 which is half of 3/4.
the radius squared is 49 times π, which is roughly 3 means the area of the base is roughly 150 ft².
This means that one third of the height cannot be more than 100 / 150 = 2/3 of a foot. That makes the height about 2 ft, much less than the reported 25 ft.