Answer:
The other lockers that were changed exactly 3 times are:
Locker 1 and Locker 7
Explanation:
Question: What other lockers were changed exactly 3 times?
Answer: Lockers 1 and 7
How?
Locker 1 was opened by a student other than student 1; it was closed by a student other than student one; and it was opened by student 1.
Same happened with Locker 7.
The relationship between these numbers is an associative relationship.