Example 1 — Two-Set Survey
Problem: In a class of 40 students, 22 play cricket, 18 play football, and 8 play both. How many students play at least one sport? How many play neither?
Setup: Let C = cricket players, F = football players. Given: n(C) = 22, n(F) = 18, n(C ∩ F) = 8, n(U) = 40.
n(C ∪ F) = 22 + 18 − 8 = 32
n(neither) = 40 − 32 = 8
Answer: 32 students play at least one sport; 8 play neither.