Question

3. A professor has had 4 of his students - student A, student B, student C, and student D-take a test

and wants to let his student's grade each other's tests. Of course, no student should grade his or her own test. How many ways could the professor hand the tests back to the students for grading, such

that no student received his or her own test back?​

Answer 1

Explanation:

including himself 4 options

excluding himself 3 options