Mathematics for IGCSE & O level - Sets (Section 3 - No. 48)
In a survey of 50 students, 20 like apples, 25 like bananas, and 10 like both. How many students like either apples or bananas?
35
40
45
50
Giải thích
Use the inclusion-exclusion principle: n(A ∪ B) = n(A) + n(B) - n(A ∩ B). So, 20 + 25 - 10 = 35. Then the number of students are 35.