Given:
Total number of students surveyed= 122
Studied in the cafeteria = 79
Studied in the student union = 56
Studied in both the student union and cafeteria = 24
To find:
Number of student those are did not study in either the cafeteria or the student union.
Solution:
Let A be the event that student studied in the cafeteria.
B be the event that student studied in the student union.
According to the question,
, where S is sample space.



Now,



So, 111 students studied in either the student union or cafeteria.



Therefore, 11 students not study in either the cafeteria or the student union.