Answer:
The gyms
Explanation:
Experimental units -
It refers to the small unit which is considered for any experimental or testing purpose , is referred to as experimental units .
Various experiments can be performed on these units , referred to as the experimental units .
Hence , from the given scenario of the question ,
Experiments are performed on the gyms , hence gyms are the experimental units ,
Number of free classes need to be calculated from the various gyms .
