Final answer:
In probability theory, the empty set symbol, ∅, represents a set with no elements. Set A in this question contains the elements 3, 5, and 6.
Step-by-step explanation:
In probability theory, the symbol ∅ represents an empty set, which means there are no elements in set A. In this case, the set A contains the elements 3, 5, and 6, with duplicate elements 3 and 5.
Calculations:
P(A) = {3, 5, 6}
P(∅) = {} (empty set)