Mathematics for IGCSE & O level - Sets (Section 2 - No. 22)
If there are 32 students in a class, and 18 study history and 20 study geography, and no student studies neither, how many students study BOTH history and geography?
8
10
6
12
Förklaring
Using the formula: n(A∪B) = n(A) + n(B) - n(A∩B). 32 = 18 + 20 - x; therefore, x = 6