Answer:
6720 different choices
Step-by-step explanation:
The ointment is put on 5 locations out of 8 locations. There are no markings or anything to differ in the 5 locations, so we can say that the order is not important. Since the order is not important we will use combination, not permutation. The other 3 locations are used for control, so it won't add to the number of possible ways.
The number of ways to put ointment in 5 of 8 locations will be:
8C5= 8!/(8-5)!= 6720 ways.