You can't tell. There are an infinite number of boxes with different dimensions
that all have the same volume.
Here are a few examples of 75 cubic feet of volume:
1 x 1 x 75
1 x 3 x 25
5 x 5 x 3
1 x 15 x 5
5 x 2 x 7.5
How many cubic feet of space are in a moving van that is 20 feet long, 7 feet wide, and 8 feet high?
35 cubic feet
It is exactly 0.5 cubic feet big because cubic feet is a measure of volume.
Noah's ark was 450 feet long, 75 feet wide, and 45 feet high. So 450x75x45=1,518,750 cubic feet, all three stories packed full. Quite a lot!
4200 cubic feet
3,000 cubic feet
4000 cubic feet.
There are: 120*45*12 = 64800 cubic feet
9.27 cubic feet
The volume of such a box is 126 cubic feet.
This cylinder has a volume of 100.528 cubic feet.
That is 65,472 cubic feet.