Answer: About 4 square bales.
Explanation:
The missing figure is attached.
The formula for calculate the volume of a rectangular prism is:

Where "l" is the lenght, "w" is the width and "h" is the height.
The volume of a cylinder can be found with this formula:

Where "r" is the radius and "h" is the height.
Then, the volume of the traditional square bale which has the shape of a rectangular prism, is:

Since the radius of a circle is half the diameter, you can identify in the figure attached that the dimensions of a large round bale are:

Then its volume is:

Finally, dividing the volumes, you get the following result:

Therefore, you can conclude that about 4 square bales contain the same amount of hay as one large round bale.