Answer:
P(A ∩ B) = 0.
a) NO
b) YES
Step-by-step explanation:
Thinking about this through Venn diagrams we can sort of understand that:
if P(A) = 0.2 and P(B) = 0.2, and P(A∪B) = 0.4.
there's no overlapping between P(A) and P(B).
(If there was overlapping then P(A∪B) < 0.4, since you'd be excluding the overlapped part from getting counted twice.
Think of it in terms of calculating areas circles A and B, if the circles were disjoint, then the sum of the areas A and B would be 0.2+0.2. But if the circles were overlapping then the sum of the areas would be 0.2+0.2-P(A ∩ B), where P(A ∩ B) is the overlapping part)
since there's no overlapping P(A ∩ B) = 0.
a) NO
events A and B are only independent when P(A ∩ B) > 0 (or overlapping)
b) YES
events A and B are mutually exclusive when P(A ∩ B) = 0 (or disjoint)
