9514 1404 393
Explanation:
Your different answers came about as a result of an error you made in the Pythagorean theorem calculation.
√(100 +100) = √200 = 14.142 . . . . same as vector calculation
The total number of cars rented for the first 5 months is
8 + 16 + 32 + 64 + 128 = 248
For this case we have that by definition, the volume of a rectangular prism is given by:

Where:
It is the area of the base
h: It is the height
So:

The volume of the prism is:

Now, the volume of the cubes is:

Thus, we divide and find the number of cubes to fill the prism:

ANswer:
n = 2.5
A≈113.1m²
...........................113.1m²