We have been given that :-
The length of a parasite in experiment A is

The length of a parasite in experiment B is

Let us write the the length of the parasite in experiment A in the exponent of -3.

Clearly, the length of parasite in experiment A is greater than the length of parasite in experiment B.
The difference in the length is given by


Therefore, the length of the parasite in experiment A is
inches greater than the length of the parasite in experiment B.